In the scene where the Servant drags the Old Man's body into the bathroom and drops him in the bathtub, the old Man (John Archer Lundgren) was already wrapped and no longer on set. Director Ryan Shovey had to step in and be the Old Man's feet and limp body for the entire sequence.
The majority of the movie, with the exception of the opening and ending book writing sequences, was filmed on green screen. The only real elements were the actors, including whatever props they interacted with (Lanterns, Mugs, Bed, Door, Fireplace (fabricated), etc). However, the bath tub was also added in post.
Director Ryan Shovey mixed three of his favorite films - Sleepy Hollow (1999), Sin City (2005) and a touch of Psycho (1960) - as the direct influences and feel for the movie.
The actual time filming was four days. However, director/editor Ryan Shovey spent 10 months alone in front of his computer doing all the post-production, excluding sound and music, for the final product.