In an interview, Alex Wolff explains that he wanted to actually break his own nose for the scene where his character slams his head into a desk. Director Ari Aster respectfully declined that offer and told Wolff they'd give him a soft, cushioned desk for the scene. When it was time for the scene to be shot, Wolff slams his head into the desk only to discover that the top was foam and the bottom was hard. He dislocated his jaw (which is a previous injury the actor has had) for the scene.
Throughout the film, several words can be seen scrawled on walls. At one point, there are two words, LIFTOACH PANDEMONIUM. Liftoach is an English transliteration of the Hebrew word 'To open'.
According to Alex Wolf, the original cut of the film could have easily pushed over 3 hours. Mostly consisting of more family dialog.
Director Cameo (Ari Aster): the voice on the phone calling Annie about her exhibit date at the Archer Gallery.
Allegedly a trailer for the film was accidentally shown at a screening of Peter Rabbit (2018) in Australia. However, a very similar event supposedly happened in 2007, where a trailer for The Hills Have Eyes Part 2 was allegedly shown to a theatre full of small children ( source: moviefone.com/2007/04/06/theater-accidentally-shows-hills-have-eyes-2-to-little-kids/amp/ ) Similar stories have been reported several times since then, even reported by reputable news sources, with a graphic horror film allegedly being shown to a group of small children, who were at the theater to see a kids' movie. In all alleged instances, the theatre is said to give free movie vouchers for all present. The similarities of these stories have made some speculate that it is nothing more than an urban legend.
Ari Aster was heavily influenced by the film The Cook, the Thief, His Wife, and Her Lover (1989).
In Peter's first scene at school, the words "Escaping Fate" is on the chalkboard with the teacher discussing it. This is a reference to Halloween (1978), where the main character discusses the same thing in class. Appropriately, this movie was released the same day as the trailer for Halloween (2018).
Toni Collete (Annie) is 22 years younger than her on-screen husband, Gabriel Byrne.
This was the fourth A24 movie to get a wide release after The Witch (2015), Free Fire (2016) and It Comes at Night (2017).
The film premiered on January 21, 2018 at the 2018 Sundance Film Festival in the Midnight section.