In an interview with The New York Times, director Alex Garland revealed that the "Christmas Wonderland" decorations in the sniper scene were not designed for the movie. Someone had built it as an attraction and decided to leave it up after the attraction was a financial failure. Alex decided to incorporate it into the movie to symbolize the chaos in the country. "If you haven't put away the Christmas decorations, clearly something isn't right."
To immerse the actors, the production used full blanks for the gunfire, as opposed to half or quarter blanks, resulting in a discharge as loud as real gunfire.
Jesse Plemons joined the cast just days before his scene was supposed to be shot due to the original actor dropping out. Kirsten Dunst, Jesse's wife, recommended Plemons to director Alex Garland.
In his sole scene, Jesse Plemons is wearing grading glasses, which are designed to eliminate all visible wavelengths entering the eyes except for red, at different shades or luminance values. This makes it very easy to tell if an object (or skin tone, in his case) is darker or lighter than another at a glance.
Alex Garland told a reporter at the premiere that the pairing of California and Texas was, in part, to obfuscate the politics but more importantly that these two states put aside political differences to challenge an unconstitutional, fascistic, and corrupt president who is killing American civilians. He said, "Are you saying extremist politics would always remain more important than a president of this sort? That sounds crazy to me."