The endings of the USA and Japanese versions are basically the same, despite the popular but erroneous story of Godzilla winning in the Japanese version. In both versions the fight ends with only King Kong emerging from the Ocean and swimming home: the only minor difference is that in the Japanese version both monsters emit roars on the soundtrack after the film ends , while in the U.S. version only King Kong's roar can be heard on the soundtrack.
When both King Kong and Godzilla crash into the ocean during the film's climax there is a big difference in the power of the Earthquake that occurs between the U.S and Japanese versions. In the Japanese version there really is no "Earthquake" but a slight tremor caused by the two big monsters fighting off of the coast. A few small rocks topple from a hill and a small sapling falls over. In the U.S version there really is an Earthquake and it's far more powerful. Not only does the quake cause the ground to split open swallowing up several houses, but massive tidal waves occur flooding the nearby valleys. Universal-International wanted a big ending and, unsatisfied with the Japanese version's small tremor, used stock footage of a violent Earthquake from a 1957 Toho film called The Mysterians to add to the U.S cut of the film.
Most of the scene in Fujita's apartment is deleted from the American version. It opens with Sakurai finding Fumiko's shoes outside of Fujita's apartment and he walks in to find Fujita and Fumiko cooking dinner as well as Sakurai wiping Fumiko's lipstick off of Fujita's lips.
In the original version, the scene where Kazuo rescues Fumiko plays out longer than in the American version. In that scene, after Godzilla passes, Kazuo criticizes Fumiko for going out to search for him and it ends with her slapping him repeatedly and calling him an idiot.
One of the running gags that was deleted from the American version were various scenes of people placing bets on who would win between King Kong and Godzilla, adding to the humor factor in the film.
In the original version, the reason that Kong was not allowed to enter Japan was due to his being considered smuggled goods. However, in the American version the reason he was not allowed to enter was because it was felt that having him and Godzilla in Japan at the same time was too dangerous.
The Japanese version does show the scene on the boat that Kazuo was on. However, for some reason it was deleted from the American version of the film.
In the original version, when Sakurai and Farue are in the jungle searching for Kong, Farue runs to Sakurai to tell him that the ship's captain gave him the news about Godzilla'a latest rampage. In the American version, there is no mention of Godzilla and it is re-dubbed to make it seem like Farue is afraid to hunt for Kong and to complain about his corns.
The scene where Kazuo yells at Kong actually is a bit longer in the original Japanese version. It is while watching Kazuo yell and raise his arms at Kong to let Fumiko go that Sakurai gets the idea to use the berries due to the fact that it reminded him of the natives ritualistic dancing.
One scene that was deleted from the American version was the one in Fumiko's apartment where she is scared by Tamie as she is watching television and she asks Fumiko if she is scared being alone while both Fujita and Sakurai are out of town.
One scene that was deleted from the American version is the scene on board the ship taking Kazuo to Hokaido to test his wire. It is during that scene that the ship receives the notice to be on the lookout for the stranded submarine.
The 1962 and 1964 theatrical versions were accompanied by a unique monaural mix (in addition to the 4-track stereo mix in 1962) that used an alternate, centered version of Akira Ifukube score recorded in tandem with the stereo version, so certain instruments and vocals are more prominent in this version. The scene of King Kong forcing a tree down Godzilla's throat also misses out on a growling sound effect from the stereo version. The mono stems were also used to construct the U.S. version's sound design. This mix was the first version released on home video in 1985 and has since been included on Toho's 2014 Blu-Ray release.
The USA version is re-edited from the Japanese original and is vastly different. New scenes featuring Eric Carter as a United Nations reporter were inserted for the USA version, replacing some footage from the Japanese release. Most of the comedy bits featuring Shoichi Hirose and Ichiro Arishima are deleted in favor of bland, action screeching to a halt U.N. news reports which are completely dissociated from the story. In the USA version, Harry Holcome recites a ludicrous idea that Godzilla is a cross of a tyrannosaurus (while pointing to an allosaurus in a children's book) and a stegosaurus. Most of Ifukube's magistral score is deleted and replaced with themes from the score of _Creature from the Black Lagoon, The (1954)_.
There was also a problem with printing, as matte lines are much more visible in the USA print than the Japanese.
The American dubbing claims Sakurai's plane crashed when it previously said he was in a boat. The dialogue here overdubs a picture of a boat. This mistake does not exist in the original.
There is a scene cut from this film. It's a brief scene that occurs while Godzilla is attacking the tanks at the arctic base. It's a far away shot of Godzilla breathing fire but this was done with a nozzle in the Godzilla'S costumes head and the effect wasn't that great so it was snipped.
Another brief scene that was cut featured Kong giving Godzilla a running "football tackle" knocking Godzilla down a hill.
A scene where there is a farewell party for Sakurai and Farue is deleted from the American version. This scene is particularly funny because Tako blasts his assistant for not inviting the press corps.
In the original Japanese version, Sakurai (Tadao Takashima) is playing drums during a recording session for a commercial when Farue ('Yu Fujiki') summons him for a meeting with Mr. Tako to inform them that they will be going to Faroe Island.
In the original version, the scene where Godzilla and Kong meet for the first time occurs as the army is digging the poison gas laced pit for Godzilla. In the American version, the meeting is rearranged so that it takes place before the pit is dug.
In the original version, the action shifts back and forth between Tokyo and the Seahawk submarine, culminating with the collision with the iceberg. In the U.S. version, the submarine sequence is shown in one continuous sequence ending with Godzilla's appearance.