Puzzled by the absence of the infamous gun that the title implies, audience are often quick to ask if they were missing some secret, deeper meaning. In actuality, the title began as an acronym during the film's early production phase. One producer suggested that the zombie idea being batted around should be given the working title: Untitled Zombie Idea. The working title survived through principle photography, and director Sam Powell decided that he was too enamored with the titles boldness to change it once the project was completed.