Media Blasters had originally intended to release the DVD of the film with not only the original Japanese version, but with the American International version, which was dubbed by Titra sound. However, when Toho heard their plans, they refused to give them permission, unless they put their internationally dubbed version on instead. Media Blasters acquiesced and the AIP version still has not had a proper DVD release.
The role of Jinguji was written for Toshirô Mifune, but his prior commitment to Akira Kurosawa's Barbarossa (1965) made it impossible for him to participate.
In preparing his script, screenwriter Shin'ichi Sekizawa used James Churchward's books about the continent of Mu. After this film was given a wide release in the United States by American International under the title "Atragon", Churchward's book were reprinted in a series of paperback editions.
Tanaka may have been inspired by "Voyage to the Bottom of the Sea" but the actual story behind "Kaitei Gunkan" dates from the late 1880's when electricity and Jules Verne were both in vogue in Japan. It was a fantasy story called "Denki-Kai" - "The Electric Light Ship."
Toho wanted the film for a Christmas release meaning that the film was made, from concept to final product, in less than four months.