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).
Tree O'Toole, 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 (2014) film.
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.
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 any other films, beyond a few brief references to them.