Dead at the Box Office (2005)

After finding a mysterious film reel hidden in their ceiling, the well-meaning staff of a struggling movie theater assume that the film is an old B-movie preview trailer and play it before a midnight screening of the timeless George A. Romero masterpiece, 'Night of the Living Dead'. When the film is revealed to be a long-dead Nazi scientist's mind control experiment, their audience of horror movie fanatics is transformed into a mob of mindless zombies with a fierce hunger for the flesh of the living! Ten survivors struggle to stay alive as the cinema is overrun by shambling hordes of the undead, while outside, ruthless government agents plot to halt the spread of the mysterious outbreak by any means necessary. Sometimes creepy, sometimes campy, 'Dead at the Box Office' pays tribute to the low budget horror films of the '70s and '80s. Combining the elements of these "B" classics with a fresh twist on the zombie origin, 'Dead at the Box Office' is a tongue-in-cheek salute to horror fans.

Source: TMDb