Dave Bautista never actually met Tig Notaro, even though in the finished film they appear alongside each other in several scenes. Notaro was inserted digitally.
Dave Bautista turned down the role of Peacemaker in The Suicide Squad (2021) in order to work on this film.
In the opening scene, two UFOs can be seen while the convoy is leaving Area 51.
The cast had to attend a zombie boot camp, mainly to learn how to handle weapons. Of them, Matthias Schweighöfer was already fully trained so he had to learn how to look less skilled.
Director Zack Snyder spent a couple of years buying every 1960's-era Canon Dream Lens he could find on eBay to give the film a soft, organic look in contrast to the harsh apocalyptic zombie landscape in the film. He also spent a year before the film collaborating with Red Studios on designing custom-made cameras that combined digital camera technology with the Canon Dream Lens.