The Mechanic (2011)

Revealing mistake: While Bishop and Steve McKenna are practicing with various firearms, a slow-motion shot in the film of Steve shooting a .50 caliber rifle shows that, while the sequence depicts him firing "live" rounds, the extracted shell casing is from a "Blank" cartridge (evidenced by the crimped forward portion of the brass casing). (00:34:15)

Dean: I'm going to put a price on your head so big that when you look in the mirror your reflection's gonna want to shoot you in the face.

Trivia: Director Simon West makes a cameo as Dean's henchman who gets killed by the garbage truck driven by Arthur.