The unedited original Japanese version of the film remains the highest attended Godzilla film in Japan. It is also one of the most attended films of all time at the Japanese box office as well as the most successful live-action science fantasy film with admission numbers surpassing Hollywood blockbusters such as Star Wars and Avatar. To this day it remains as the 13th most attended film of all time in Japan. The heavily re-edited US version that inserted new actors and deleted several scenes from the original was just as much of a success at the US box-office as well.
In the fight scene, when King Kong throws Godzilla over his shoulder, suit actor Shoichi Hirose didn't throw an empty suit, but actually threw it with Haruo Nakajima still inside as this was Hirose's way of proving he was the stronger of the two. This move was one of the many martial arts influences in the fight choreography since Godzilla suit actor Nakajima practiced Judo and was given the opportunity to choreograph the fight.
For decades, a myth has circulated that the outcome in the original Japanese version was different from that of the American version. The earliest record of this rumor was in the American fanzine Spaceman which wrote that those who saw the movie in "some Oriental sector of the world" were given a different ending. However this is not true with author Steve Ryfle noting that "What is different about the Japanese and U.S. versions of King Kong vs. Godzilla is not the ending, but most everything else." Similar to Godzilla, King of the Monsters! (1956), most of the original Kingu Kongu tai Gojira (1962) was heavily re-edited for it's release outside of Japan. Producer John Beck inserted several new scenes with American actors directed by Tom Montgomery in a news report subplot that was never present in the original version. Writers Bruce Howard and Paul Mason rewrote much of the story with the new dialogue often straying from the original Japanese script, with much of the intentional humor being eliminated. Beck also had editor Peter Zinner restructure the entire narrative and replace the original soundtrack with stock music from Universal. The only musical piece that survived was the Island chant. Universal has never bothered to actually release the un-edited version of the film meaning that the 1963 American re-edit is the most widespread version instead of the actual 1962 Japanese original.
This film introduced Godzilla's more well-known and standardized high-pitched roar (which was actually a mix of two of his original 1954 roars, sped up by several cycles). This was a way to tone down Godzilla's darkness from the previous two movies. This ultimately became Godzilla's roar for the remainder of the Showa Godzilla film series, and was also used in the VS/Heisei and Millennium Godzilla film series, albeit with tweaks.
The film features the Davy Crockett, a portable missile-launched nuclear weapon developed by the United States. At the time, this weapon was still classified.