The film's wilderness setting, 'The Cauldron of the Moon,' was shot in a stretch of Ontario wilderness that had been burned out by a forest fire five years earlier. Plenty of the charred trees left from the fire can be seen in the film.
This movie was shot in continuity.
The original script left the killer's identity unknown.
The severed deer's head was real.
The scene with the guys trudging through the swamp was shot in a single take.