Fairuza Balk wore hair extensions in the movie, and she even had special aquatic hair clip ins for the pool scene.
Originally the film would be released in September 2001, but due to the 9/11 attacks it was pushed back to 2002.
Josh Hartnett was originally cast in the role of Tino but was allowed by the producers to drop out when he won the role of Danny in Pearl Harbor (2001).
There's a scene with Leon (Stephen Dorff) dreaming that his brother Bobby (Brad Renfro) died of a heroin overdose. Brad Renfro died in 2008 of acute accidental heroin and morphine intoxication.