Writer and actress Jamie Alvey got the idea for Bystanders following the high profile Brock Turner case in 2016. The first draft was completed in the spring of 2017 and was subsequently revised and entered into festivals as a screenplay for the next few years.
The longstanding poster for screenplay festivals was designed by Alvey's best friend from college, Emily Fabrizio. The scene depicted was filmed three years to the day of the poster's creation.
Alvey wanted to incorporate a split diopter shot, but cinematographer Chance Madison said they didn't have the technology on hand, unfortunately.
Alvey had long since had certain shots in mind, taking cues from some of her favorite movies, including Drive (2011), M.F.A. (2017), 10 Cloverfield Lane (2016), Hush (2016), The Last House on the Left (1974/2009), Absentia (2011), Rose Plays Julie (2019), and Violation (2020).
The earliest draft of Bystanders from 2016 had Ellie named Marie instead. However, Clare and Gray have always kept their names.