The shot of the mother being killed was altered. Originally, a big cloud of blood flew out of Evelyn. John Singleton thought that this would be too much for the audience to handle.
Pre-production for the film included teaching the four actors how to ice skate for the hockey scenes. Mark Wahlberg and Garrett Hedlund were the only leads that already knew how to skate.
Director Cameo: (John Singleton) makes a cameo, appearing as the goalie during the hockey scene on Thanksgiving.
Larenz Tate turned down the role of Jeremiah.
The squibs in the Mercer House Shootout were originally meant to be more bloody, but due to a mix up with wire working, they appear tame.
The rosary Bobby is seen wearing on the lake is Jack's. Jack can been seen wearing it during the shootout.
In the original screenplay, Angel carried Sofie upstairs during the shootout, and placed her into a steel tub. John Singleton liked the idea, but it was dropped due to time.
In the first draft of the screenplay none of the brothers dies. In the second draft Jack is killed. The screenwriters thought that it would add more of an intense dislike for Victor Sweet and a more emotional state of the rest of the brothers.
For the Mercer House Shootout, there were over 450 squibs rigged throughout the house, all of which resulted in debris and glass falling on the actors.
John Singleton: makes a cameo, appearing as the goalie during the hockey scene on Thanksgiving.
Based on the Henry Hathaway western The Sons of Katie Elder (1965) starring John Wayne and Dean Martin.
The word "fuck" is used 62 times throughout the movie.
Ethan Hawke, Matt Damon and Ben Affleck all turned down the part of Bobby. The part eventually went to Mark Wahlberg. Ethan Hawke loved the script but could not commit to it because of scheduling conflicts. Matt Damon and Ben Affleck both said no because they found the script to be "ultra-violent".
Most of the teasing with Jack was improvised by Mark Wahlberg and Garrett Hedlund.
Almost all of Mark Wahlberg's lines were improvised. Garrett Hedlund had difficulty improvising his lines, so John Singleton and Mark Wahlberg helped him through it.