NEW YORK, NY - JUNE 04:  John Cusack attends Meet The Filmmaker, John Cusack, Bill Pohlad and Brian Wilson, "Love And Mercy"  during the Apple Store Soho Presents at Apple Store Soho on June 4, 2015 in New York City.  (Photo by John Lamparski/WireImage)
TV - Movies
The Ending Of
The Stephen King adaptation makes it completely clear that room 1408 and everything that goes on inside is not a part of Mike's imagination. Many of the haunting events in 1408 have to do with past visitors or victims of the room, but it eventually gets personal, mixing the real-world horror of trauma and grief with supernatural hauntings.
Room 1408 Was Real
The official theatrical release ended with Mike's survival, his reunion with Lily, and the listening of the tape. But the movie also had a director's cut ending where Mike die’s in a fire that destroys room 1408 and according to the movie's Wikipedia page there was a third ending which was slightly different from the director’s cut.
Different Endings
The source material from “1408” is from a short story, so the film had to expand and fill out Mike's experience in the room at the Dolphin to fill the length of the movie. Probably the biggest change between the story and the film is the addition of Mike's backstory where he had an estranged wife and daughter.
Movie vs Short Story