The original concept of this film comes from a short film of the same name. In fact, Claire's campfire ghost story is explaining the events of the short film.
Shot in 12 days.
It took Jonjo Tweddle 4 hours in the make up chair to transform into the Shimian.
Guy's Cliffe in Warwick UK that doubled for Blatty Manor is reportedly haunted with regular reports of ghost sightings and supernatural activity, this made some cast and crew uneasy when shooting in the underground tunnels late at night.