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The Biggest Plot Holes In How I Met Your Mother

With a nine-season run that contains more than 200 episodes, "How I Met Your Mother" is among the longest-running serialized comedy shows of the century. The series follows five friends; architect Ted Mosby (Josh Radnor), lawyer Marshall Eriksen (Jason Segel), kindergarten teacher Lily Aldrin (Alyson Hannigan), news anchor Robin Scherbatsky (Cobie Smulders), and suit lover Barney Stinson (Neil Patrick Harris) as an older Ted (voiced by Bob Saget) explains to his children how he met their mother. 

With plenty of storylines ranging from Ted being left at the altar to Barney going from serial dater to long-term boyfriend, not every detail was ever going to line up perfectly by the end. It's hard to keep track of everything that happens between so many main characters and the side characters they get involved with over the show's run. Fans haven't always been pleased with the decisions made in the writers' room, including which couples stick it out until the end of "How I Met Your Mother," and sometimes viewers get confused when a nugget of new information contradicts a previously established detail. Grab a gas can because the Monstrosity Sport, sadly, does not get great gas mileage, and let's go down memory lane and look at the biggest plot holes, continuity errors, inconsistent character behaviors, and other dubious elements of "How I Met Your Mother." 

The specific timing of major events

Because of the relatively lengthy timeline of "How I Met Your Mother," viewers see plenty of major events in the gang's lives. Although sometimes the specific timing of certain events gets a little muddled. For example, in the Season 1 episode "Purple Giraffe," Robin tells Ted she moved to New York in April of 2005. In the Season 9 episode "Last Forever – Part 1," we see a flashback to September of 2005 when Robin tells Ted she moved to the city two months prior. This places the time of her arrival in July, not April.  

Another major date-related inconsistency — one that's even confirmed by showrunner Carter Bays — is the point when the yellow umbrella switches between Ted and Tracy (Cristin Milioti). During the Season 3 episode "No Tomorrow," Barney and Ted go out for St. Patrick's Day festivities, which usually transpire on or around March 17. When Tracy is remembering this night seasons later, she says it happened in April. Doesn't that seem a touch too late to celebrate this particular holiday? Bays addressed this goof on Twitter, commenting with confidence that he was "pretty sure" St. Patrick's Day was in April that year, while demanding that the rest of us never, ever check into that information. 

Barney and Robin's wedding date

There is also a major inconsistency surrounding a date that could alter the timeline of the entire final season. In the Season 8 episode "Band or DJ?" the date of Robin and Barney's wedding is confirmed as May 25, 2013, with Ted picking it out and Robin confirming that's the date she's going with. Any digital calendar will tell us that May 25 of 2013 was a Saturday. When the first episode of the final season opens, though, it says its events are beginning on the Friday morning before the wedding, with 55 hours left until the ceremony begins, which makes the wedding Sunday, not Saturday. 

However, the last episode of Season 8, "Something New" provides a bit more clarity on the matter. While they admire the house he renovated, Ted tells Lily that he's leaving the day after the wedding. As they are getting in his car, preparing to drive off to the wedding at the end of the episode, Lily asks what time he leaves on Monday. That means the writers confirmed the wedding was on Sunday. So, why did Ted originally state the date as the 25th — a Saturday? Did Robin and Barney change the date of the wedding sometime between "Band or DJ?" and "Something New?" The discrepancy hasn't been explained and it continues to be a continuity error to this day.

Barney's ability to drive

As a kid who grew up in Staten Island, Barney never has a chance to learn to drive. Like many New Yorkers, he relies on public transport. However, his inability is revealed by Ted in the Season 2 episode "Arrivederci, Fiero" when he tries to teach Barney how to drive during a transit strike. The lesson goes poorly. Barney manages to drive approximately 3 mph in a parking lot and still freaks out. As he recounts the experience to the group, he uses some choice words to describe the car, including "death trap."

However, in the very next episode, "Moving Day," Barney steals Ted's moving van to prevent him from moving in with Robin. How did Barney steal it? Did he drive it away? Based on his comments following his very recent driving lesson, it doesn't seem like he ever got his license, which means he couldn't legally drive it away. 

This isn't the only time audiences caught Barney driving despite his lack of credentials. In Season 5, when Marshall and Lily are hunting for Barney's doppelganger, they spot him as a cab driver. They found out later the cab driver is actually Barney, who uses driving a cab as a pretext to meet women. The womanizer is actively driving the cab while he explains the story to Marshall, and this is only one of many times we see him drive a car after Season 2. How is he driving the cab? When did Barney finish learning to drive? 

Barney's rules for wearing suits

When the gang is preparing to attend Mark's funeral in the Season 2 episode "Monday Night Football," Barney explains one of his rules for wearing suits. "Suits are full of joy," he explains to his friends. "Suits are for the living." While everyone else is dressed up for the solemn occasion, Barney is wearing a t-shirt, hoodie, and sneakers, none of which are black. During the viewing, he comments that the suit Mark is wearing must be "frightened," implying that the suit is both sentient and that it doesn't know what's happening.

Skip forward to Season 6, where Barney wears a suit during a funeral. This goes against his personal rule. But this funeral isn't just for anyone; it's for Marshall's dad Marvin (Bill Fagerbakke) in arguably one of the saddest scenes from "How I Met Your Mother." Is the frequent suit wearer honoring the gravitas of the situation and trying to appear supportive of his friend during a hard time? Has he changed his rules regarding suits at funerals? Audiences are never given an explanation.

This isn't the only time Barney changes his tune about his personal concept of suit etiquette, either. In Season 4, the avid wearer of suits claims he even wears a silk suit with a "sleeping cravat" to bed. But when Lily stays at his apartment for a bit in Season 2, he is wearing a t-shirt and sweats. Did he switch to wearing a suit to bed sometime between the two seasons? Did Lily catch him when it was at the cleaners? No one will tell us.  

Ted's bacon allergy

While everyone is preparing for Barney and Robin's wedding in Season 9's "Rally," Ted tries bacon, supposedly for the first time. According to Ted, when he was little, his mother told him he's allergic to bacon. The veracity of that notion comes under scrutiny when Ted and Marshall must seek out a cure for Barney's hangover. To make a long story short, curing Barney's hangover requires someone to eat an entire pan of bacon as soon as possible, and Ted says he is unable to do so because of his allergy. Marshall explains that his bacon allergy is "a lie [his] mother made up so [he'd] eat healthy as a kid." As Ted remembers his other supposed allergies — including an allergy to Halloween candy — he realizes Marshall is right. 

Ted tries bacon and laments what he's been missing all this time, and the voiceover states that this is Ted's first and only time eating bacon. But is it really? There are instances of Ted happily taking plates of food that contain the crispy breakfast meat throughout the show. When Lily's dad Mickey (Chris Elliott) makes breakfast for her and her husband at their inherited house in "46 Minutes" from Season 7, Ted rushes to grab a plate full of bacon and pancakes. 

Reddit user u/Juce93 also pointed out that Ted can be seen holding a plate of bacon in the first episode of Season 5. Viewers don't see him eat it, but it does create questions surrounding the true nature of his imaginary bacon allergy.

Lily's allergies

It seems like multiple characters on "How I Met Your Mother" sometimes get confused about what they're allergic to. At one point, Lily claims to be allergic to barrel resin, but she admits she made that up because she doesn't like Marshall's decoration choices. But Lily makes no such confession about her supposed dog allergy, which is revealed in the Season 2 episode "World's Greatest Couple." When Lily returns to New York after her summer away, she ends up having to stay at Barney's apartment for a bit. It would make more sense for her to stay with Robin, but Robin tells Ted and Barney that Lily is allergic to dogs, and Robin has several in her apartment. 

However, in other episodes we see Lily hanging out with Robin at her apartment and petting her dogs without any issues. In the Season 6 episode "Unfinished," Lily even says she remembers having a dog as a child. It seems weird that her parents would let her have a pet she's allergic to, doesn't it? Is her dog allergy easily controlled with medication that didn't happen to be available during the events of "World's Greatest Couple?" How could she live with a dog as a child but not as an adult? It doesn't make sense, especially since it's described as a real allergy, not a fake one.

Lily and Marshall's toothbrush(es)

Lily and Marshall admit in the Season 5 episode "Perfect Week" that they use the same toothbrush, and Robin and Ted correctly describe this practice as "super weird." This new information takes a bizarre turn when Ted realizes that he had been accidentally using the same toothbrush throughout the eight years he was living with the couple. When it's factored in that Robin also used the toothbrush sometimes when she stayed the night, the total count of people per toothbrush was a four-to-one ratio.

Other than the gang's clearly troublesome dental hygiene practices, fans noticed an error. In the Season 1 episode "Zip, Zip, Zip," Marshall and Lily use separate toothbrushes as they get ready for bed. Is the group misremembering the timeline of the toothbrush, or getting the number of toothbrushes in the bathroom wrong, or is merely a continuity error? Whichever it may be, it is a confusing detail to look back on and is never explained.

Robin's enthusiasm for guns

You don't have to watch a ton of "How I Met Your Mother" before you know which character you're most likely to find at a shooting range. The series never hides Robin's opinion on guns. At the start of Season 2, she takes Marshall to a shooting range as he deals with his breakup with Lily. She tells Marshall that she goes to the range whenever she's feeling "lonely or depressed" and that her father taught her how to shoot when she was young. But in order to avoid a conflict, she's keeping her love of guns a secret from Ted, who isn't a fan of that sort of thing. 

Later in the season, she moves her subscription to "Guns and Ammo" to her office when Ted moves in. During the call about her change of address, she even notes that she's written letters to the magazine. In the Season 6 episode "Baby Talk," fans even spotted the character wearing a necklace with a handgun pendant on it.

That's all well and good, but how do we account for Robin's reaction to a gun in the Season 1 episode "The Limo?" When Not Moby (J.P. Manoux) randomly pulls a gun out of his jacket, Robin looks as shocked as anyone. She physically cringes away and puts her hand up to block her face. This could seem like a curious reaction coming from someone who is presumably comfortable around guns. On the other hand, there's obviously big a difference between a gun in the controlled environment of a shooting range and a gun carelessly waved around by a stranger for no apparent reason in the back of a packed limo. It's also certainly possible the writers didn't decide Robin would be into guns until they started working on Season 2, but whatever the case, it's never been cleared up.

Robin's sport of choice

Robin isn't only known for going to the shooting range; she's also the gang's resident hockey player. In Season 4, viewers are treated to a flashback where she's a member of the otherwise all-boys youth hockey team, and even gets caught kissing one of her teammates by her dad. She compares different aspects of life, like her tendencies in her dating life, to hockey concepts. Robin even plays hockey with her sister Katie (Lucy Hale) the morning of her wedding, breaking a lamp in the process. 

While Robin is frequently associated with the classic Canadian ice sport, in the Season 1 episode "The Slutty Pumpkin," she tells Ted on the roof of the apartment building that she played tennis in high school. Specifically, she starts her story with the phrase, "I never played any team sports." Obviously, hockey is a team sport. And the goof isn't explained away somehow, even though it easily could've been — maybe Robin started playing tennis after hockey, or maybe she wanted to wait until she knew Ted for a while longer before revealing her hockey-oriented past. Whatever the case, we may never know the complete truth of Robin's teenage tennis and hockey careers.

What happened to Gary Blauman

Gary Blauman (Taran Killam) is a name "How I Met Your Mother" fans will recognize. He's known as a member of the legal team at the secretly evil AltruCell Corporation, and even mentors Marshall when he interns for the company for some extra cash. He's introduced in the Season 1 episode "Life Among the Gorillas" and returns occasionally throughout the show's nine-season run. 

In Season 3, Barney tells a story of Gary quitting after a confrontation with his boss. The tale ends with Gary's death. After we hear this, Blauman continues to make appearances at Goliath National Bank (GNB) and even attends Robin and Barney's wedding. Barney is known for his outlandish stories, so it can be written off that he exaggerated what happened to Gary to drive his point home to Marshall. Series co-creator Carter Bays confirmed on Twitter in 2014 that Barney's story was a lie, but fans in the comments still voiced their confusion. They didn't understand why Marshall doesn't question this story despite becoming a full-time employee with GNB and running into Gary on a routine basis. As far as Marshall knows, Gary had at least quit, even if his friend embellished the dying part. When was Gary brought back on? Was Barney's entire story a lie? 

What was the Cockamouse?

The Cockamouse is introduced in the Season 1 episode "Matchmaker," spotted in the apartment. Lily is convinced it's a cockroach, while Marshall is pretty sure it's a mouse. "It has six legs, a hard exoskeleton, like a roach," Lily tells the group after it makes another appearance. Marshall adds that it has a tail and "gray-brown tufts of fur," just like a mouse, and that it is roughly the size of a potato. Hence, the name "Cockamouse" is born.

Despite popping up throughout the series, viewers never find out which species the Cockamouse actually belongs to; we never see it clearly enough to deduce what it could be. That wasn't for lack of effort on the characters' parts, either. In the episode where the Cockamouse is introduced, Lily and Marshall catch it and plan to take it Marshall's friend at Columbia University, hoping he can identify what kind of creature it is. When Marshall arrives at his friend's school, the Cockamouse has escaped, and his friend thinks he's pulling a joke. The series never confirms what The Cockamouse actually is, so audiences are just left to speculate. 

What happened to Tracy

The basic premise of the series is what we're seeing is one big flashback as Ted tells his children how he met their mother. That's right there in the name of the show. When Tracy McConnell is finally introduced, before long, the audience sees her fall ill. Viewers watch as Ted accompanies her to the hospital, as the two wax poetic about their lives, and even about how they got engaged at the Farhampton Inn. 

Despite knowing most of her life story and all her quirks and ukulele songs, the show never shares exactly how she dies. All that's said is she got sick and passed away. All nine seasons have culminated in knowing her and seeing her and Ted have their happily ever after. While they were together about a decade before Tracy passed, and Ted still ends up with Robin in the end, the show gives fans what they waited for only to yank it away with very little explanation. 

Not knowing what Tracy was sick with isn't technically a plot hole, but it feels like one because of how much the show built up her introduction. Tracy's tragic end was an unexpected tonal shift, especially when the rest of the show feels like it's preparing us for a totally different ending.