Alex Chehrazi has said that Black Christmas (1974) and Mulholland Drive (2001) were the main inspirations for this story.
Just like her character Hazel McKinnon, Cindy Girard claims that she had a similar experience in the past where an unknown man was constantly harassing her with eerie and disturbing phone calls.
Shot in 5 days.
The location for the Taxi scene was not secure until a week before shooting. Initial locations were constantly being changed throughout production as a permit could not be obtained; thus having to delay shooting for that scene until a spot was finally secure.
The first draft of the screenplay was completed in November 2014.