Curiosidades

Shortly before his death in 1993, director Ishirô Honda was said to have mentioned that this was his favorite of all his films.

Yoshio Tsuchiya was offered the lead role but turned it down, instead opting to play the Mysterian leader. Tsuchiya, known for his work in the films of Akira Kurosawa, enjoyed working on Toho's science fiction films. and preferred to play alien characters.

An American viewer reported the film to the FBI after taking their children to see it, claiming it was communist propaganda. In particular the individual voiced concern over the Earth Defense Force, which depicted international cooperation between the US, USSR, and other nations. The individual wrote how they were "deeply disturbed" by the film's themes and suggested to the FBI to list films they deemed "insidious, anti-American, brain-washing propaganda".

This was one of the last films to be distributed by RKO in the US. When RKO ceased operations, most of the first run was handled by MGM.

Martin Scorsese has expressed admiration for the imagination of this film and other Toho science fiction films when he wrote the forward to the director's biography.