Since the movie was based on a series of conversations between Patrick Brice and Mark Duplass, most of it was improvised. This led to a lot of scenes being shot, and as a result, the footage was screened in front of their peers. This eventually pushed the psychological black comedy into a psychological horror film after taking the advice of their friends. There is also footage of at least three other alternate endings.
They filmed this in a week, with only a 5 page outline.
The Peachfuzz mask used is Forum Novelties 59449 Night Wolf Mask.
The film is almost totally improvised. The film's 'bible' was only 'bare bones' - i.e., driving a car, while videotaping a dialogue of the trip.
The first of a trilogy of 'Creep' films. Creep 2 was released October 24, 2017, while the third installation in the franchise is in development.