The location that first inspired the idea of the film became unavailable three weeks before principal photography. 6 days later, a hospital in Brooklyn was secured to shoot in, delaying principal photography by only a week.
Shot in 20 days.
While shooting a scene in the morgue, actress Tationna Bosier squeezed a dead roach in her hand in order to get herself into the scene emotionally in a hurry. She nailed it in 2 takes. It was affectionately dubbed the "Dead Roach Approach."
In the scene where Sarah (Whitney Kirk) is being attacked in the hallway; an insert shot is shown of her grabbing a pen. The hand in the insert shot actually belongs to actress Anelisa Durham, who worked with director Brian Kazmarck on his short Game Theory. The insert was shot 8 months after principal photography wrapped. It was officially the last shot done for the film.
The film contains over 30 VFX shots. Though they are subtle and practically unnoticeable, they took a considerable amount of time to get right so that they would go unnoticed.