In order to make the actors feel what the characters were going through, all of the bathroom scenes were shot in chronological order.
Was filmed in 18 days.
Director James Wan wanted the camera movements to reflect the two main characters' emotions and personality. He filmed Dr. Gordon with steady controlled shots and Adam as handheld shots to capture their emotions of the situation.
Director James Wan took a gamble and took no upfront salary for the film and opted for a percentage instead.