The Real Reason Superman & Lois Took So Long To Address Its Arrowverse Canonicity
Since it's on The CW and based on DC characters, it's easy to assume that "Superman & Lois" is connected to the Arrowverse, despite its various differences to other shows in the shared universe. However, for much of its two-season existence, the show has done its level best to avoid addressing the situation. In an exclusive interview with Looper, Ian Bohen (who plays Mitch Anderson in the show) noted that he would love a crossover with "The Flash" or "Batwoman," but neither has materialized so far.
In its sophomore season, the show finally reveals whether it takes place in the Arrowverse, albeit in a stealthy way that's easy to miss. In the "Superman & Lois" Season 2 finale, Sam Lane (Dylan Walsh) notes that other Arrowverse superheroes don't exist on the version of Earth the show takes place on, although there are all sorts of powerful heroes in other versions of Earth.
The fact that "Superman & Lois" takes place in a different Earth than most Arrowverse shows isn't exactly shocking, and given the franchise's history of bringing alternate-reality superheroes together when the situation requires it, it doesn't necessarily rule out Arrowverse-adjacent antics. So, why did the show wait for two whole seasons to reveal its status in the grander scheme of things?
Changed plans and DC decisions kept the show's Arrowverse status on hold
According to "Superman & Lois" showrunner Todd Helbing (via Den of Geek), the show never intended to play its Arrowverse cards so close to its chest. The Arrowverse connection was originally intended to be obvious, right down to that "Batwoman" crossover Bohen wanted. However, this changed before filming even started, in the interest of keeping things as streamlined as possible — both behind the cameras and in front of them. Being its own thing helped the show to deal with the COVID-19 pandemic and its restrictions, and allowed it to exist relatively free from shared universe baggage.
Helbing says the alternate Earth idea "Superman & Lois" ultimately used was pitched pretty early in the game, but DC wanted to wait a little bit longer before dropping the revelation.
"I think because of the pandemic, and just our want to really just be our own show, and really put our own stamp on the Superman mythos, all those references got stripped out," the showrunner said. "I had a conversation with DC, in season one about us not being on the same planet, as the rest of the Arrowverse, but I couldn't tell that to anybody, because I was asked [to hold it] until the finale. DC is unbelievably awesome to work with, but they're a big corporation with a lot of balls in the air ... but certainly the fans over the seasons had a lot of questions [and] they were becoming frustrated. I wish we could have told everybody sooner, but we just couldn't."
As Helbing himself notes, there's still absolutely no reason why other Arrowverse characters couldn't turn up in "Superman & Lois," in one way or another. For now, however, it seems that this version of Superman is the sole powered hero of his planet.