Gerard Butler and his crew are loosely based on former ATF agent Jay Dobyns, who consulted on the film. Dobyns is best known for his undercover work and his willingness to infiltrate crime organizations, much like Gerard Butler's character. Dobyns makes a cameo in the film at the bar Donnie works at in LA, closing his tab at the bar.
Gerard Butler gained twenty-five pounds for his role, as recommended by director Christian Gudegast.
Prior to filming, two separate boot camps were run in order to get the cops and the robbers in shape for their respective roles with both groups training separately to enforce a rival atmosphere. Interestingly, each group was trained differently by military consultant Paul Maurice.
Christian Gudegast's original cut of the film was closer to 160 minutes and featured a different ending.
As Merriman's crew is driving the armored truck away after the opening scene, the getaway car following the truck has a taillight out. Later in the movie while briefing his team, big Nick states that Merriman served ten years in prison after he "gets unlucky with a taillight" following a robbery.