Trivia: When Lorraine Warren is dreaming about the demonic nun in her house, the demon actually reveals its name in 2 ways. The first is the way Lorraine realises at the end of the movie (written in the Bible). However, the audience is another way-the gold letters on the bookshelf behind her also spell out the name "Valak."
Trivia: SPOILER WARNING. The character of Kevin was originally intended to be in the film "Unbreakable" (to which this film is revealed to be a sort-of sequel in the final twist scene), but he was removed for thematic reasons, as it was felt that his presence took away focus from that film's true villain "Mr. Glass." Writer/Director M. Night Shyamalan has stated his intentions to make a third film in the "trilogy" that will feature Bruce Willis' character David Dunn from "Unbreakable" being forced to confront Kevin, who will be his ultimate "supervillain."
Trivia: The film's production was quite troubled. A crewmember named Ricardo Cornelius was killed in a freak accident when he was crushed by a Humvee and a stuntwoman named Olivia Jackson was severely injured, with her face being "de-gloved" and sustaining may injuries and fractures which resulted in the loss of her right arm. Thankfully she survived and made a full recovery and the doctors were able to surgically mend her face and other injuries.
Trivia: The movie was filmed in secret and revealed in 2015, when it was shopped around to distributors. Netflix acquired the movie and released it as a Netflix-exclusive title in 2016. However, it was removed from the service in 2023 once the initial licensing deal expired. Director Mike Flanagan has stated his intention to try and shop the film around for a physical media release on DVD/Blu-Ray in the near future.
Trivia: A somewhat comical behind-the-scenes fact: During filming, in order to get the actors to jump and act scared at the right moments, director Adam Wingard would occasionally secretly carry around an air-horn and "honk" it when the actors weren't expecting it. (And then obviously dub over a scarier sound effect in post).
Trivia: When Lockhart is in the sensory deprivation tank, the nurse that does a poor job of keeping an eye on him is reading "Der Zauberberg" by Thomas Mann, which obviously has at that point a common premise with the movie (the main character goes to a sanatorium in the Alps just as a visitor but ends up as an inmate). The novel was inspired by Mann's visit to his wife at a Swiss sanatorium which happened in 1912, same year as the picture fully unveiled in the finale.
Trivia: At the very beginning of the movie, as the car drives along towards the town, the music to Stephen Kings' The Shining plays.
Trivia: Jason Mewes was originally set to play the "Brahtzies", but had to drop out due to finding the makeup required for the roles far too claustrophobic.