A painting Lady Godiva, the story that initialized the term "peeping tom", can be seen beside The Janitors front door.
The Director decided against most dialog and naming the characters to emphasize the isolated feeling of the main character.
During the filming of the final scene, the Victim was dragged across the entire apartment floor six times on her back with no padding.
Although The Killer is technically only seen once, every time The Killer enters the apartment, be it physically or via footage, his presence is characterized by the sound of static.
The 2 minute continuous take climax was originally 16 shots but due to time constraints the Director and Assistant Director decided to reduce it to a single one. It only took 5 takes to get it correct after the Director of Photography had heard of the change the day of.