Director Bill Rebane began shooting the film in 1961, but ran out of money. Years later, director Herschell Gordon Lewis bought the incomplete film to team it with Moonshine Mountain (1964) as a double feature. Lewis filmed some additional footage, added narration (which he did himself), and released it in 1965. Many of the actors didn't come back for later filming, which explains why most of the characters disappear without explanation. One actor changed so much that he ended up playing his own brother.
At one point, when a phone supposedly rings, the sound effect is obviously a person making a noise with his mouth.
Featured in a 1993 installment of Mystery Science Theater 3000 (1988). The cast and crew considered it the worst film ever featured on the show.
The film is regarded as being one of the all-time worst.
Henry Hite was 7 foot 6, but the director wanted the monster to be 10 feet tall, so Hite was always filmed from a low angle.