Writer/Director Alex Chung gathered the cast and crew to brainstorm ideas for making a grindhouse film before settling on Werewolf Assassin. For inspiration, the cast and crew were shown trailers for I Drink Your Blood (1971), Cannibal Girls (1973), Blacula (1972) and The Toxic Avenger (1984).
The idea for the fake trailer "There's Something Terribly Wrong With The Formerly Amorous Marissa Parker" came from the director's frustration with the countless copycats of The Exorcist (1973) that he kept finding while researching grindhouse trailers.
Writer/Director Alex Chung's friends and fellow filmmakers Tim Biemann and Nate Wilson were originally tapped to contribute fake trailers to the film.
The fake trailer "Database X" came from an ad-lib by Reuben John Tumanguil and together with the director actually came up with an entire plot for the fake film that also acts as a prequel to Werewolf Assassin.
Even though traditionally werewolves appear at night (during full moons), the werewolf scenes in this film are all during the day.