A promotional sign was posted at every theater showing this film which stated: "FOR YOUR PROTECTION! We will not permit you to see these shockers unless you agree to release the theatre of all responsibility for death by fright!" Moviegoers actually had to sign a "Fright Release" before they entered the theater.
Director Del Tenney was apprehensive about the films combination of the teen beach movie genre and the monster horror genre, not knowing how it would go over with an audience. Tenney said he was admittedly surprised by the films success.
According to director Del Tenney, there were only two complete monster heads created for the film, which is why in most shots of multiple monsters you don't see their heads clearly. For the climatic scene at Fingle's Quarry the shot of the horde of monsters running through the woods was created by superimposing different takes of the complete monsters together.
For a meeting in which Del Tenney was going to show the film to executives from Twentieth Century Fox to see if they would pick it up, Tenney brought in some folks to wear the monster suits for promotion. One of the monsters just happened to be in the restroom when an executive from Twentieth Century came in. The gentleman freaked out at the sight of the monster Tenney recalled. Everyone had a good laugh about it and Twentieth Century Fox released the film.