El mundo bajo el terror

Gamera's role as a guardian of children came from director Noriaki Yuasa's own traumatic experiences growing up as a child during WWII. He mentioned that all the adults and teachers he knew would constantly implant to him the importance of nationalism and Imperial Japan's ambitions, only to abandon it all after Japan's defeat. He recounted the story of how of a teacher of his switched from being a outspoken Nationalist into an advocating Communist. Yuasa had also been a child actor and the behavior he witnessed from them lead him to develop a disapproval of actors in general. These sentiments were carried into the making of Gamera, which Yuasa conceived as the only entity children could have faith in.

In the English language version, special effects director Yonesaburo Tsukiji is mistakenly credited as Yonesaburg Tsukiji.

Not released in the USA until 1985, to home video and television, by Sandy Frank under the title GAMERA. To that day, the only way to (partially) see it was the movie Gammera the Invincible (1966), which used the special effects footage from the original Japanese film but most scenes involving human actors were replaced by new ones featuring an American cast. The Sandy Frank version, one of his usual dubbing jobs, was the whole original Japanese footage except for the opening credits sequence, replaced by English translated credits superimposed over an image of moving ocean water. Another difference is that in the Frank dub the names of some characters are Americanized (i.e. Toshio is renamed Kenny).

Edited into Gammera the Invincible (1966)