Shot in ten days.
This movie and Cat-Women of the Moon were made using the some of the same sets and costumes. The two films were then released within one day of each other.
This was initially intended as a pilot film for a TV series to be called "Ring Around the Moon". When science-fiction movies suddenly became popular, producer Jack Seaman added enough footage to the film to bring it up to feature length. This was done without the knowledge of writer Robert A. Heinlein, and he disowned the result.