From the screenplay stage and all the way through to production, The Dark (1979)'s antagonist was an abused, autistic child who had been locked in an attic for his entire life. In the original script, his house burned down, allowing him to escape and take vengeance on the outside world. Toward the end of the shoot, the film's producers decided to capitalize on the success of Alien (1979) and demanded extensive re-shoots to change the killer into an extra-terrestrial.

Director John 'Bud' Cardos replaced Tobe Hooper during production.

The television station is KFVI. The last part "FVI" refers to this film's production company, Film Ventures International. When Shelley is by the movie theater at the beginning of the film, two posters can be seen for The Devil Within Her (1974) (aka "Beyond the Door") and Il medaglione insanguinato (Perche?!) (1975) (aka "The Night Child"). These Italian horror films were distributed by Film Ventures International.

Riffed by the guys from MST3K under the Rifftrax name; Michael J Nelson, Bill Corbett and Kevin Murphy.

Trailer narrated by Percy Rodrigues.