Trivia: Hollywood actress Reese Witherspoon was a fan of the novel and purchased the rights, intending to play the role of Amy herself. However, once David Fincher was attached as director, she opted to serve only as a producer, realizing she wasn't right for the role.
Trivia: Originally intended for theatrical release, this film ultimately had to be released through streaming after the North Korean government threatened to retaliate against the United States. A cyber crimes group allegedly tied to North Korea also hacked Sony's emails and made threats against theaters that had planned to show the film.
Trivia: Part of the inspiration for the film came from a friend of writer/director Jennifer Kent. Her friend, a single mother, had a young son who like many children was terrified of non-existent "monsters" he thought were lurking in his home. Kent then had the idea to turn this into a film. What if a child was terrified of monsters lurking in their closet, under their beds, etc... except they were real?
Trivia: Carla Azar plays the drummer Nana. She is a real drummer and plays in a band. She plays beside the drums, bass, guitar and keyboard, and sings.
Trivia: Funded mainly through the use of online crowd-funding.
Trivia: Josh Brolin Dwight had been previously portrayed by actor Clive Owen in the first film. As originally planned, Brolin would play the character prior to his plastic surgery, while Owen would reprise his role and play Dwight post plastic-surgery. However, Owen was unavailable to reprise his role, and thus prosthetics were used to attempt to make Brolin's post-surgery look subtly similar to Owen's facial structure.
Trivia: The fancy Mercedes is not "the only one in America" (as John Madec said on the movie) but the only one in the world. The car was borrowed for the purpose of the movie by one of the owners of the Formula One team McLaren and was shipped by air from Germany. Hence German licence plates often seen during the film.