In the Japanese version, there is an unused voice clip of the announcer saying "Jigglypuff!", however Jigglypuff's Japanese name is Purin. This seems to hint that the developers planned to release the game in the west from the start, as Jigglypuff is the only character whose name is different in English and Japanese. This voice clip is also different than the one used in the international release of the game.

The congratulation screens were absent in the Japanese version of the game.

After the Super Smash Bros. release in Japan, Nintendo began a poll to gauge public interests for future roster additions. Of the top ten, seven have since been added, with the remaining three left out. James Bond was most likely left out due to legal reasons, as he is not originally a video game character and belongs to a more strict estate. While not playable, Mew and Toad both make cameos with Mew being a rare Pokeball result and Toad being used in one of Peach's attacks in later games.

One of Peach's Castle's hazards is a bumper, which is mostly used as an item. Coincidentally, this is the first stage to use an item as a hazard, and have a hazard outside of its own universe; Peach's Castle is from Mario and the Bumper is from Super Smash Bros.

In an early version of the game, Peach's Castle lacked the sign, the bridge, and the sliding stone blocks.

In the background of the Mushroom Kingdom stage, Green Koopa Troopas can be seen walking back and forth across platforms. This contradicts every Mario game to date where Red Koopas turn when coming to an edge while Green Koopas will simply walk off the edge. This would later be corrected with the stage's reappearance in Super Smash Bros. Ultimate.

Captain Falcon and Ness are the only playable characters who do not have a stage based on their respective franchises.

Super Smash Bros. was developed with a low budget, had low publicity when it launched in Japan, and was even intended to be Japan-exclusive. However, the game's success prompted Nintendo to localize it for international audiences.

For some reason, the announcer says Fox differently in the Japanese version than in the International version, even though Fox is a character with no name differences in any region.

The Fighting Polygon Team is called Dummy Corps in the Japanese version.

According to a page on the Japanese Super Smash Bros. site, Mewtwo was planned to be playable, but was cut; Bowser and King Dedede are also mentioned as having been cut, though no other information is available.

Charles Martinet is misspelled as Charles Martinee in the game's credits.

It is impossible (at least without the use of a cheat device) to clear all eight digits in the points counter in 1P mode.

Captain Falcon has the most usable costumes in the game, with six. Most characters have four or five. Yoshi also has six, but only four are usable outside of hacking, as two only appear in the single player mode.

When the Announcer introduces Metal Mario, his voice becomes slightly metallic. Although it may just be to place emphasis on Metal Mario's metal composition, the Announcer's voice sounds noticeably deeper and it does not change like that for any other character in Classic Mode.

Luigi takes his appearance from Super Mario World, having purple overalls rather than dark blue. However, this is not true of his artwork.

Captain Falcon's "Congratulations!" screen is the only one to use a pre-existing image from an original game, in this case, the first unlockable title screen from F-Zero X.

Captain Falcon is the only playable character that doesn't use his own head for his stock life icon. Instead, he uses a Falcon.

While all other characters show their skeletons upon being hit with an electric attack, Samus's suitless outline becomes visible instead.

In the character select screen, the characters (excluding unlockable characters) are placed in the order of when they first appeared in their respective titles, starting with the oldest, Mario and Donkey Kong, and leading to the most recent, Pikachu.