The Poison Mushroom in the Super Smash Bros. games is the only item borrowed from another series whose appearance does not stay true to its original franchise. In the Mario series, poison mushrooms have distinct colouring from other mushrooms, but in the Super Smash Bros. series, they look similar to Super Mushrooms in order to purposefully confuse players. The differences between the two items are nearly unnoticeable - the Poison Mushrooms are only slightly less red and have a meaner look.

In each game the texture for Ness's yoyo includes the year of the game's release. "2001" for Super Smash Bros. Melee, "2008" for Super Smash Bros. Brawl, and "2014" for Super Smash Bros. for Nintendo 3DS and Wii U.

Pit's hammer swinging animation is meant to resemble how he moves around and attacks with a hammer in Kid Icarus and Kid Icarus: Myths and Monsters.

In the Super Smash Bros. series, Yoshi is usually one of cast's heavier fighters. He even outweighs Samus and Ganondorf in the PAL versions of Super Smash Bros. Melee and is on par with Wario in Super Smash Bros. Brawl. Despite this, Yoshi is usually labelled as a lightweight or middleweight character in the Mario Kart and Mario Tennis spin-offs.

In German versions of the Super Smash Bros. games, Popo had his name changed to "Pepe" because the word "popo" means "butt" in German.

In the November 2014 issue of GameInformer, it was revealed that Masahiro Sakurai takes photos of a pose-able action figure to create the moves for new characters whenever one is being made. The image shown is the action figure poses used to make the Mii Fighters' moveset.

One of the longest works of literature in the English language is a Super Smash Bros fan fiction. At 4,047,350 words, it's about 8.5 times the length of the Lord of the Rings books.

Jigglypuff is the only character in the series to be instantly K.Oed when its shield breaks.

Throughout the series, Kirby can transform into a pink block with eyes from the SNES game, Panel De Pon (Known as Tetris Attack Internationally).

In each iteration, Fox's voice has been provided by the same voice actor who played him in the most recent Star Fox game.

N64 - Shinobu Satochi - Star Fox 64 (Japanese Voice Actor)
Melee - Steve Malpass - Star Fox Adventures
Brawl - Jim Walker - Star Fox: Assault
Wii U/3DS - Mike West - Star Fox 64 3D

Shulk and Pac-Man are the only characters in the entire Smash Bros. series to not have a green palette swap option.

Mentioning Project M, the name of an unofficial modified version of Super Smash Bros. Brawl to reintroduce elements from Super Smash Bros. Melee, by name on any of Nintendo's Miiverse channels will trigger an automatic ban for discussing "criminal activity".

Series creator, Masahiro Sakurai, has stated that both Super Smash Bros. Melee and Super Smash Bros. Brawl were developed with the mindset that there were to be no more sequels after them.

Captain Falcon is the only character in the Super Smash Bros. series whose availability status has changed with each sequel, being unlockable in both the original Super Smash Bros. and Super Smash Bros. Brawl, but available from the start in Super Smash Bros. Melee and Super Smash Bros. for Nintendo 3DS and Wii U.

Domestic and international popularity polls are used when deciding who to add into a Super Smash Brothers game. After that, certain questions such as whether a character can present something interesting and whether they're a good representative of their series are asked.

When Kirby takes Zelda's ability, he wears the headdress Zelda wears as a child in Ocarina of Time, despite the fact Zelda is an adult in Super Smash Bros and the headdress appears nowhere else in the game.

In the Japanese versions of Super Smash Bros and Super Smash Bros: Melee, the Beam Sword sounded similar to a Lightsaber from the Star Wars series. This was changed during localization for other regions. In Super Smash Bros: Brawl, the sound effects have been kept the same for all versions.

In all of Captain Falcon's appearances within the Super Smash Bros. series, his red color swap is actually the outfit of Blood Falcon, his evil clone in the F-Zero games, complete with the correct insignia.

Aside from Pikachu and Jigglypuff (whose costume accessories change from game to game), Samus is the only character to have one of her team-based costumes change between games: In the original Smash Bros. and Melee, Samus wears her default (orange) costume when she is on the red team, but in Brawl, her pink costume is used instead. This could be due to the fact that in her Zero Suit, her default costume color is blue. So they needed to give her a new costume that would depict both forms in something closely resembling Red.

Pikachu is the only playable Pokémon in the Super Smash Bros. series to have a visible gender difference in the Pokémon series. Male Pikachus look like the one in Smash Bros, but females have a small indent in their tail, which vaguely looks like a heart. However, gender differences in Pokémon were introduced in Generation IV, which came out after the first Super Smash Bros. and Melee. Therefore, though not proven, it can be assumed the Pikachu in Brawl is male.

Pokémon Trainer is the only character that has a custom name in their original series to not be given a default name in Brawl, and is instead given a generic name. It is clear from the character design that the suitable default name would be "Red" as he is named as such in Pokémon Gold and Silver, and again in the remakes which were released after Brawl. The reason this was done is unknown.

Kirby uses a different dash attack in each of the first three Super Smash Bros. games. In the original Super Smash Bros., he performs a slide tackle. In Melee, he performs "Burning Kirby" (an ability seen in some Kirby games, and merged with the Fire ability in others), while in Brawl, he performs Yo-Yo Kirby's "Break Spin" from Kirby Super Star.

Pikachu is the only character in the entire Super Smash Bros series to only have four costume color options in the first three games.

Snake, Mega Man, Donkey Kong, Link, Sonic the Hedgehog, and Little Mac are the only characters in the Smash series to appear in another fighting game.

•Snake appeared in Dream-Mix TV World Fighters as a playable character.
•Mega Man has appeared in the Mega Man Power Battle Series, a few Capcom VS games (mainly the Marvel vs. Capcom series) and Street Fighter X Tekken (in his "Bad Box Art" form).
•Donkey Kong also appeared in Punch-Out!! for Wii as a boss.
•Sonic appeared as a playable character in Sonic the Fighters and Sonic Battle.
•Link appeared in the Gamecube version of SoulCalibur II.
•Little Mac appears in Punch-Out!!

In SSB and Melee the first syllable of "Samus" is pronounced /sɑ/ ("saw"). However, in Brawl, it's pronounced /sæ/ ("sah"). This change in pronunciation is consistent with the way Samus is pronounced in Metroid Prime 3: Corruption.

Jigglypuff's eyes are blue in the Pokemon series, but green in the Super Smash Bros. series, the same color as a shiny Jigglypuff.

In all of her Smash Bros. appearances, Peach is depicted with a ring on her middle finger, which is absent in other games.

All lines spoken by Marth in Melee/Brawl/Wii U and 3DS are in Japanese. These are what they all are translated:

Marth's taunt - "Everyone, please watch me!" ("みんな、見ていてくれ！")
Marth's counter - "There!" ("そこだ！"), "I won't let you!" ("させるものか！")
Marth's victory poses - "This time, victory is mine, right?" ("今回は僕の勝ちだね。"), "Today, too, I managed to survive." ("今日も生き延びることが出来た。"), "There's no way I can lose!" ("僕は負ける訳には行かないんだ。")

He also has an unused sound file in the Debug Menu of the game which is "Let's Dance!" ("レッツダンス！")

Mario's Cape attack can be used on a taunting character to make them face the other way in ways that are otherwise impossible, like making Wario face the screen while doing his side taunt.