The film was originally conceived as three stories that would play out separately, but all have the unearthed remains of Satan being the linking factor between them. The stories of Peter Edmonton and his mad fiance, the possessed village children, and the Judge's battle with evil were all at first supposed to take place independently. However, when the script was rewritten, it was decided that the plots should be combined to create one central story.
At one point, both Peter Cushing and Christopher Lee were suggested for the role of the Judge but were considered to be too expensive. Other actors discussed included Donald Pleasence and Michael Gough.
On her first day of filming, star Linda Hayden cut her foot badly and had to be rushed to a local hospital for stitches. She stated in an interview that due to being in costume and makeup for her devilish scene, some older folks at the hospital thought she was either an angel or a devil and that they had passed over.
The movie was a commercial disappointment. "It never made much money," said director Piers Haggard in an interview. "It wasn't a hit. From the very beginning it had minority appeal. A few people absolutely loved it but the audiences didn't turn out for it."
Actor Simon Williams said while shooting the scene where he's attacked by the furry claw, "they had a little insert shot of my hand reaching for the dagger and I was doing a lot of business of inching my fingers forward and twitching them. Piers said, 'Cut! Cut! Cut! Simon, don't overact with your fingers."