Special effects director Eiji Tsuburaya wanted the battle between Godzilla and Anguirus filmed in slow motion, but a camera technician accidentally undercranked the camera instead of overcranking it, resulting in the movement appearing faster than reality. Tsuburaya thought it looked interesting and decided to use it in the film anyway.
Upon its release, this film garnered better critical reception in Japan than Godzilla (1954) did. According to the director of the first film, Ishirô Honda, film critics at the time dismissed science fiction films and the notion that the genre could have themes and ideas. Because of this, he recalled the first film being heavily criticized by film critics while this film was better received by them.
Godzilla (1954) became such a huge hit that Toho immediately produced a sequel. Specifically, it was a decision by Toho's executive producer, Iwao Mori. He had returned to Japan after working on the film Madama Butterfly (1954) and had learned about the monumental success of the first film. His orders to producer Tomoyuki Tanaka were to "make another one". Even though numerous special effects scenes were required, Toho had the film ready in less than six months after the first film was released. Despite its rushed production, the film was another box office hit and remains both one of the most successful Godzilla films and the 30th most attended film of all time at the Japanese box office.
When Godzilla and Angurus fall off Iwato Island and into the ocean, Haruo Nakajima and Katsumi Tezuka were actually inside the suits. Crew members were positioned outside the frame to pulled them to the surface when the take was completed.
This is the first film in the "Godzilla" series in which Godzilla fights another giant monster, although Anguirus is quickly killed by Godzilla.