The 3D portraits on the character select screen are based on character artwork from some of their home games. Mario's render is from Super Mario 64; Link's is from his artwork for The Legend of Zelda: Ocarina of Time; Donkey Kong's Donkey Kong Country artwork is the basis for his Smash portrait; Yoshi's comes from Japanese artwork for Yoshi's Island; Kirby's is from Kirby's Adventure artwork; Fox's is taken from Star Fox 64; Captain Falcon has a 3D realization of artwork from F-Zero X; Pikachu and Jigglypuff are 3D versions of Pokemon Red & Blue concept art; Samus Aran's comes from Super Metroid; Ness's is a redone done version of his Earthbound art; And Luigi's appears to be taken from Mario Kart 64.
Marth was originally going to be part of the roster, but was scrapped due to time constraints. He later made his appearance in Super Smash Bros. Melee as an unlockable character.
On Hyrule Castle, the Maxim Tomatoes item never appears. If it is the only item put on using the item switch, all boxes and capsules will either explode or be empty.
The game's official US website refers to the Bob-omb item as "Bomb Soldier".
The bedroom seen in the intro and in the scene shown after completing 1P Game has a door that is always completely unseen. Since the camera focuses mostly on the table where Master Hand puts the dolls on, the door stays hidden behind the camera.
Captain Falcon and Samus share multiple attack animations.
In the Japanese release, the attack sounds are real punching noises. It's likely this was changed to keep the game family-friendly.
In the Mushroom Kingdom stage, pausing the game and looking off to the left or right of the stage to see outside of the standard gameplay field of view, it's possible to see walls with warnings signs reading "Danger" on them, warning the player of the stage's boundary. This appears in the stage in Super Smash Bros. Melee too.
The banner in the background of Saffron City that says "Got a Catch 'em All!" in the Japanese version, missing the second T. This was changed to "Gotta catch 'em all!" in the Western releases. The font also appears to have been rewritten to accommodate this. Also, the Silph sign on the Building on the right is Romanised as Silf in the Japanese release.
There is an unused sound of the announcer saying "draw game", suggesting this may be an early name for Sudden Death, or possibly that sudden death originally didn't exist.
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, six have since been added, with the remaining four left out. James Bond, and Banjo and Kazooie were most likely left out due to legal reasons, as they belonged to separate companies. While not playable, Mew and Toad both make cameos with Mew being a rare Pokeball result and Toad being seen 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. Coincidently, 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.
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.
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.
According to an interview with Satoru Iwata, Masahiro Sakurai intended for the characters to use Final Smashes in this game. It was taken out due to hardware limitations. This concept was held off until Super Smash Bros. Brawl. Going in the debug menu you can find 3 sound files. 2 of them of Ness saying "PK" and "Starstorm!". The third is Captain Falcon saying "Come On!".
Super Smash Bros. was originally going to be a fighting game called 'Dragon King: The Fighting Game' for the SNES using the Super FX chip, a microchip that rendered 3D polygon graphics. It didn't feature any of the 12 playable characters in the final version. Instead, it was going to be the first game of an entirely new series.