The enormous popularity of Toho's giant monster films led Daiei to issue publicity stills showing the Pairans as gigantic creatures that towered over buildings. In the film, the Pairans are human sized.
This film wasn't released in the United States until 1967.
This was the first color tokusatsu science fiction film produced in Japan. It beat Toho's science fiction spectacle, Ishirô Honda's The Mysterians (the first tokusatsu film in widescreen), into theaters by a year.