Was associated with a controversial short horror movie contest, in which, Warner Brothers would legally own the contest winner's idea for three years (and have the option to develop a full feature film out of it), while only being obligated to compensate the contestant with $100 USD and a chance to meet the director David F. Sandberg (if available).
The woman who played the adult Annabelle Higgins is usually a stunt woman and has been a stunt for Vera Farmiga in the other Conjuring films. She also played the adult Annabelle Higgins in the first Annabelle film.
David F. Sandberg was initially reluctant to direct the film, due to his general dislike of horror sequels. He changed his mind when it was clear he would be making a standalone prequel, with no major obligations to connect it to the larger franchise beyond a few brief references to the other films.
The design of the framework around the front door of the farmhouse shows regular crosses and upside down crosses, which may symbolize how there's both holy influence and dark forces at war in the home.
A subplot had sister Charlotte (Stephanie Sigman) confessing to Esther Mullins (Miranda Otto) that she had once given birth to a son. She had given him up for adoption, but later found out that the boy had drowned at the age of seven, when he got trapped beneath the ice of a frozen lake. Later, Charlotte hears strange noises in bed, and when she holds a light under it, she sees a shadow on the wall of the boy, desperately clawing at the ice above him. The scenes were filmed but ultimately deemed unnecessary for the film.
The doll that Janice, who now calls herself Annabelle, is given at the end of the movie is a replica of Raggedy Ann doll the Warren's removed during an exorcism. For the movie, a creepy looking porcelain doll was used to appear more sinister. This real doll is still kept on display, at Lorraine Warren's home, and can be seen in photos and footage of the Warren home.
There was originally much more of Mrs. Mullins (Miranda Otto) in the film's final act; after her violent death, her corpse would reanimate and become the main antagonist for much of the rest of the film. It was originally Mrs. Mullins who threatens Linda (Lulu Wilson) while she is in the dumbwaiter, and who attacks the girls in the barn; however, in re-shoots, Mrs. Mullins' role was replaced by the horned demon and the scarecrow.