Trivia: Chicko, the dog, was 11 years old and blind. The dog was constantly bumping into furniture so it was very hard for the film crew. They only got one take of Chicko walking through the doggie door with out bumping into the wall or a piece of furniture and that is the take that was in the movie.
Trivia: In the scene where Mort sees Kent's Cadillac in the driveway, he taps on the window. Mort was told that Kent was dead, Shooter had gotten to Kent, Kent was told that he was supposed to wake up when the glass was tapped. Mort's reaction was real. When Johnny Depp (who played Mort) looks back off screen, he is glaring at the director, who was laughing his head off.
Trivia: In the book "Secret Window, Secret Garden" the ending is completely different. Mort Rainey dies, without killing Ted and Amy. They live and get married. Also they believed, at the end, that Shooter was a real person. Totally different from the movie. Everything else was almost word for word.