Winona Ryder acquired the rights to the novel herself, then spent seven years trying to get the movie made.
Angelina Jolie avoided any communication with Winona Ryder when making the movie, claiming that if she saw anything human about Ryder, she would not have been able to act out the sociopath character Lisa Rowe as effectively.
Much of the movie was filmed at the Harrisburg State Hospital in Pennsylvania, which was still in use for treatment of mentally-ill patients until it closed down in 2006.
Director James Mangold states in the DVD commentary that the original cut was three hours long. This version has not been shown publicly nor released on any media, however, the DVD contains 15 minutes of the scenes deleted from the final cut.
Angelina Jolie revealed in an interview that she genuinely thought she was the only character who was sane in the entire film, and that's how she played it. She said, "I was actually almost upset when people said I was so good at playing insane because I never thought she was insane. She was just incredibly honest, which, I guess, made her seem crazy."