As part of his research for the film, director Marc Forster actually sat in an electric chair and was horrified to see the nail marks that the electrocuted prisoners had involuntarily scratched into the wood.
In a 2009 interview with Monster's Ball producer Lee Daniels, he revealed that Wes Bentley did not actually turn down the role of Sonny Grotowski, as was reported at the time. What actually happened was that Bentley committed to the role but then pulled out at the very last minute, and Lionsgate gave them only 48 hours to find a replacement (who turned out to be Heath Ledger). In 2010, Bentley admitted that his erratic, unpredictable, and unreliable behavior throughout much of the 2000s had been caused by a longstanding addiction to heroin.
In the rockumentary Lemmy (2010), during a conversation in a bar with Motörhead lead singer Lemmy, Billy Bob Thornton states that he was paid half a million dollars to appear in this movie, and after it became a big box office success, he subsequently received a check in the mail for a further 2 million dollars.
Angela Bassett purportedly turned down the role of Leticia, stating "I wasn't going to be a prostitute on film..." However, Lions Gate Production President Michael Paseornek and the film's producer Lee Daniels rebut Bassett stating that she was never even offered the role, and was already committed to another film.
The gas station Hank buys is initially called Clement's and he tells Leticia it is on Prospect Street. Clements and Prospect are two neighboring streets in North Vancouver, BC Canada, where Lions Gate Studios are located.