Although it was shot in Denmark, producer Sidney W. Pink had the dialog spoken in English. When the finished film was turned over to American International, Pink was informed that the dialog would be re-looped. AIP head Samuel Z. Arkoff felt that what he called the "sing-song Scandinavian accents" would have U.S. audiences laughing. Pink objected and threatened to file suit. After Pink had other industry professionals view his version of the film, the lawsuit was dropped and AIP released the film in an edited and re-dubbed version.
Denmark's first and only "Monster" movie.
Footage from this movie was used in the American animation-show "South Park" (1997) in episode #704: "Cancelled".
Many of the elements in the script for this film were originally intended for the failed Volcano Monsters project, which was also written by Ib Melchior.