The idea for Annulment came from Bryan Stumpf's ex-wife, with whom he remains friends. While snowbound in the same house during a polar vortex in Upstate NY, joking about the novelty of a divorced couple enduring cabin fever together, she said, "You know what would be a funny movie? A divorced couple stuck in the same house during a zombie apocalypse."
Writer, producer, director Bryan Stumpf and his ex-wife, Laura Halferty - the inspiration for Harold and Kerry - make an appearance in the movie. When Harold (Mike Larose) and Kerry (Kat Scicluna) stand in front of the fridge, as an Infected crawls in through a window, there are two pictures visible on the fridge behind them - both pictures show Bryan and Laura, taken at a time when they were still married.
The lighthouse that appears in the film, the Tibbetts Point Lighthouse, located in Cape Vincent, New York, is the actual lighthouse where writer, producer, director Bryan Stumpf and Laura Halferty - the inspiration for Harold and Kerry - were married.