During Godzilla's rampage through downtown Tokyo, one of the buildings he destroys is the Toho Theater. In fact, some fans who were watching the film in that theater actually thought the theater was being attacked and tried to run out of the theater.
The sound department tried numerous animal roars for Godzilla but felt they were unsuitable for an animal of such immense size. Akira Ifukube came up with Godzilla's roars by rubbing a coarse, resin-coated leather glove up and down the strings of a contrabass (double bass), and reverberated the recorded sound. Also, Godzilla's thunderous footsteps were made by beating a kettle drum with a knotted rope.
George Lucas cites this film's miniatures as an inspiration for his effects in the Star Wars films.
Was the most expensive Japanese movie ever made at the time of its release.
The electrical towers that Godzilla melts with his radioactive breath were actually made of wax. The special effects crew melted them by blowing hot air on them, as well as shining hot studio lights on them for the white-hot effect.
One of the most famous legends regarding the production of this film has Ishirô Honda and Eiji Tsuburaya on the observation deck of what was then one of Tokyo's skyscrapers. They were planning Godzilla's path of destruction. Other visitors on the deck became concerned when portions of their conversation were overheard. The pair was stopped by authorities and questioned.
Because of the complexity of the production, the entire film was storyboarded. This is believed to be the very first time this was done for a Japanese film.
The name Gojira is a combination of the Japanese words for gorilla (gorira) and whale (kujira). The monster was so named because his original design was that of a gorilla-whale monster, which is recounted by people who worked on the film. 'Shigeru Kayama' (who was hired by Tomoyuki Tanaka to write the original story) recounted in a book of memoirs he published in Japan, that Tanaka told him the creature would be a sea monster that was "a cross between a whale and a gorilla". After producer Tanaka saw the American monster film The Beast from 20,000 Fathoms (1953), he got the idea to turn Godzilla into a dinosaur monster. Despite the physical change the name of the monster was kept. There has always been a legend that Godzilla was named after a hulking man nicknamed Gorilla-Whale who worked at Tôhô, but this is untrue. Not only is there no evidence of this man even existing, but the various stories about him kept changing through the years (he worked as a stagehand, he worked as a PR man, etc.). According to Kimi Honda, wife of Ishirô Honda, the Gorilla-Whale man was just an inside joke between her husband and various others on the Tôhô lot - specifically producer Tanaka.
The movie's opening scene was inspired by the Lucky Dragon incident, where the fishing boat known as the Lucky Dragon strayed too close to what was named the most powerful nuclear test ever and was contaminated with radiation. A crew on board a fishing boat, going about their normal day, suddenly a bright flash of light catches their attention, and they are soon bombarded with radioactivity. The only difference is that the boat catches fire and sinks in the movie. If you look closely at the life preserver, you will see the marking "No. 5". This was a reference to the ship Lucky Dragon No. 5, which was one of the inspirations for the film.
Originally when Gojira (Godzilla) makes his first appearance, there was supposed to be a bloody cow in his mouth. After reviewing the test shots, Masao Tamai, the cinematographer, felt it was far too graphic and convinced director Ishirô Honda to re-film the sequence without the cow.
In one of the early script drafts, Doctor Yemane was written as a very dark and sinister character. In fact, one of the original ideas was to have Yemane sneak into the control room that controlled the electrical towers and sabotage the attempt to electrocute Gojira (Godzilla).