For the sex scene on the stairs, David Cronenberg was concerned about the two actors getting hurt on the hard wooden steps. He asked his stunt man whether or not he had any stunt pads to soften up the stairs. The stunt man laughed, saying that in the twenty years he had been working as a stunt man, no director had ever asked him for stunt pads for a sex scene. Pads were not used for most of the scene however, and in the shot when Edie is naked on the bed with bruises visible on her back, make-up was used to hide the amount of bruises that Maria Bello received from the scene.
During an interview, Viggo Mortensen stated that during the shooting of the first bar scene with Ed Harris he could not stop laughing, and as a result, the scene had to be re-shot several times. Due to Viggo Mortensen's behavior, Ed Harris completed the scene without pants; he only wore his underwear, yet this cannot be seen as the bar table impedes our view. Thus, Viggo Mortensen had to act seriously while Ed Harris was not wearing any pants, and this is the scene that is used in the movie.
The mobsters were originally supposed to be Italian, but after the casting of Ed Harris and William Hurt, David Cronenberg decided to change the mob to Irish. He felt Harris and Hurt wouldn't make convincing Italians.
The fictitious town that the film is set in (Millbrook, Indiana) is named after the town where the film was actually shot (Millbrook, Ontario, Canada). The scenes set in Philadelphia were actually shot in Toronto, Canada.
The actors who played the two robbers in the cafe came up with their own backstory about why the men were travelling together. According to them the older man was the younger man's uncle and was taking him across country after the younger man had been released from prison.
According to Bart Beatty, in his book "David Cronenberg's A History of Violence, Cronenberg did not know that this movie was based on a paradox Press/Vertigo Comics graphic novel until after he signed on to direct. While it is unclear as to his stance on comic books in general, he has stated that he does not care for superhero comics/films, feeling they are all adolescent at their core, no matter how dark, edgy or intelligent critics and fans alike feel they are. He did not care for the Dc Comics film "The Dark Knight" (2008) as it was still about a guy in a cape and a mask (despite praising the technical prowess).
In a deleted scene, Tom dreams of shooting Carl Fogarty in the diner, but the scene was cut because David Cronenberg thought it was too reminiscent of the director's own previous Videodrome (1983). In the scene, Fogarty, his chest blown open by a shotgun, the exposed ends of ribs smoking, nonetheless rises from the floor and aims a handgun at Tom. Along with the deleted scene, the director and crew joke that Fogarty should pull the gun out of his gaping abdomen, an "homage" by the director to himself and to "Videodrome".
In the scene where Mortenson's character meets his brother's henchman in the bar. Two TVs in the background are showing harness racing from Woodbine Racetrack in Toronto. The distinctive voice of long-time Ontario Jockey Club announcer Frank Salive can be clearly heard in the first few moments of the scene.
In the original script, the front yard confrontation between Tom, Carl Fogarty, and Carl's thugs was meant to be more brutal. The script called for Tom to rip off one thug's nose and then take his gun and kill everyone else, including Carl Fogarty. David Cronenberg wanted this movie to be realistic and not stylized in any way.
The scene in the restaurant where Tom foils the robbery was cut to some extent. The original cut had the younger shooter being shot over seven times and having the older shooter being shot in the head twice. It was cut, not because of the MPAA, but because of David Cronenberg himself. Cronenberg thought the scene was way too much and thought it glorified violence, which he was against.