The film's title references the cuckoo, certain species of which are brood parasites — they lay their eggs in other birds' nests, deceiving those birds into incubating, feeding and rearing their young, much like the monster in the film.
Originally slated for release on 3 May, it was postponed until 9 August for reasons that have not been disclosed.
There was a short-lived misunderstanding online that the film would be released in four separate parts after Neon issued four character posters labelled "Part 1", "Part 2", "Part 3" and "Part 4".
In a 2024 interview with Fangoria, Tilman Singer described filming the shadow jump scare: "…we had to film the whole sequence of cycling down the road in a single night. We shot in Germany, and I think we only had about four and a half hours of night-time before the sun rose. It was a race against the sun. It was quite difficult to do, and it was all practical. We already had a trailer with a crane and the camera and everything to shoot from different angles, and then we put our bicycle onto the trailer to capture low-angle shots. In the end, they had to give us stronger streetlights. I don't know how many feet or metres away, but our cinematographer created a 3D simulation to work out how far apart they should be, where you can see her shadow and the shadow of the person running, but not the camera vehicle. It was quite tricky with that shadow creeping in, the hand coming up. That was one of the last things we did that night. We were almost unable to pull it off because it was such a fragile thing to get absolutely right, where you see her shadow passing by and then the other person's shadow coming. When you get these things right, they're so rewarding. …Kalin Morrow was actually running behind Hunter Schafer while she was on the bike; that was all there."
