Edward Norton spent time with real prisoners in the Southern Michigan Correctional Facility. He adopted his character's accent and cornrow hairstyle from the prisoners. Norton inserted phrases he heard from the prisoners into the dialogue.
The prison scenes were filmed at the State Prison of Southern Michigan. At one time this was the world's largest walled prison. Since its closure the site has become a popular filming venue, having also served as the prison location for Tony Goldwyn's Conviction (2010).