The trivia items below may give away important plot points.
This film was the first time John Carroll Lynch had portrayed a serial killer. The second time was in when he played the suspected Zodiac Killer, Arthur Leigh Allen in the movie Zodiac. The third time he was cast as Twisty the Clown on the fourth season of television series American Horror Story : Freakshow.
The filmmakers attempted to have the film end back at the prison, including having a prison riot where Sheriff Ryan is killed by the inmates, but no one could figure out, story-wise, how to get Miranda back there, since she had already escaped from there twice earlier in the film. Director Mathieu Kassovitz ultimately decided that getting the characters out of the hospital for the climax was a good idea.