Josh Boone intended this film to be the first in a trilogy, with the second film to be an alien invasion movie featuring the alien mutant Warlock, and then the third and final installment to be a supernatural, apocalyptic horror movie based on the X-Men comic event "Inferno" (demons invade the Earth and Magik plays a major role). After Disney's purchase of Fox, all X-Men-related films in development were cancelled, including Boone's trilogy.
The majority of the film was shot on location at Medfield State Hospital, in Massachusetts. This hospital was the state's first mental asylum, and most of the cast and crew were unsettled by the location.
Josh Boone admitted that he found shooting to be stressful, as he felt "a bit neutered" because he had to tone down the film from his original "full horror" ideas.