Director/star Ben Affleck was most concerned that the actors have authentic-sounding Boston accents. When Blake Lively read for the part of Krista, she sounded so authentic that he asked her where she grew up in Boston. She was born and raised in California.
The original cut was 4 hours long. After realizing that the film would never appeal to wide audiences, Ben Affleck cut the film down to 2 hours, 50 minutes in 3 days. The studio and producers loved it, but they wanted the film to be no longer than 2 hours, 10 minutes. Eventually, Affleck cut the film down to 2 hours, 8 minutes. While Affleck was happy with the theatrical cut, he said that an Extended Cut on the DVD and BluRay will feature deleted scenes on top of the cut footage. He also said that while the theatrical cut of The Town is a close adaptation of the novel 'Prince of Thieves', the extended cut is more true to the book.
Before the movie was released, Ben Affleck praised Jeremy Renner's performance. He even jokingly stated that if ever there was a bad shot or performance from someone else in a scene, editing could easily cut to Renner looking at a napkin in order to make the scene work. Jeremy Renner later would go on to receive an Academy Award nomination for his performance.
While filming of the first robbery, Ben Affleck would sometimes direct while in full costume, including the skull mask. Rebecca Hall was unable to keep a straight face, and found it difficult to take direction from him when he was in costume.
In one scene, there is a shot of the TV playing a movie where a white truck rides into a Drive In Movie Lot, this is a scene from the movie "Heat", a movie that is also about bank robbers being chased by an obsessed detective.
Victor Garber's short appearance in the film was a favor for his friend Ben Affleck. Garber worked for five years with Affleck's wife, Jennifer Garner, on the series Alias (2001), and Garber officiated at Garner and Affleck's wedding.
In July 2011, during U.S. Congressional debate over raising the country's national debt ceiling, Republican Party leaders used a clip from this film, specifically a scene between Ben Affleck and Jeremy Renner, as a motivational device in meetings to rally party unity. It was immediately lampooned by comedic commentators Jon Stewart and Bill Maher.
Ben Affleck originally wanted Mark Wahlberg for the role of James Coughlin, but he was busy shooting The Fighter (2010), so the role went to Jeremy Renner, who ended up receiving the Oscar nomination for Best Supporting Actor.
The studio heads initially wanted the novel's ending, in which Doug is mortally wounded during his shootout with Fergie and dies in Claire's arms in her apartment. The ending was filmed, but test audiences approved the theatrical version, in which Doug survives.
Dez's death scene had to be signed off by Major League Baseball (MLB). According to Ben Affleck, one cut included blood spattering the ambulance. MLB decided the scene was too violent, and Affleck used the other cut, featuring less blood.