Despite not appearing in the Subspace Emissary, Crazy Hand's trophy is placed in The Supspace Emissary category.

The Sothe trophy states that he is a swordsman - this is untrue, as Sothe wields knives and daggers.

Moltres' trophy says that its first game was Pokemon Gold and Silver, when it really originated in Red and Blue.

On the Kyle Hyde trophy, it states that he is a former detective. This is not true; Kyle is a former cop who worked for the NYPD.

The Bonkers trophy says that Kirby could get the Smash ability by inhaling him. This is not correct, as he only gives the Hammer ability.

Lucas' home village is stated to be call "Tazumili" in the US version, but in Mother 3 the village is actually named Tazmily. This was corrected in the PAL version of Brawl.

During the opening cutscene, hidden characters are not shown until they are unlocked, with the exception of Ness, Marth, Sonic and Snake.

The Pokemon Trainer has an unused jumping animation. Some fans have speculated he may have been playable on his own, but it seems more likely that this jumping was planned to help him traverse large areas like The Subspace Emissary.

In the Subspace Emissary mode in Super Smash Bros. Brawl, there is a cutscene where Ridley grabs Samus and drags her along the wall. He only lets go when Pikachu zaps him with a thunder bolt. This cutscene seems to have influenced a similar scene in Metroid: Other M, where Ridley does the same, only to be shot by Anthony.

In the unlockable All-Star mode, the order in which opponents are fought is based upon the order in which their game series were released chronologically, beginning with Mr. Game & Watch and ending with Captain Olimar.

Characters were originally going to visually show battle damage. You can see some of the injured player textures in the game's files.

According to Masahiro Sakurai this would have tied into a mechanic where a characters armor and other equipment would be damaged during the fight, putting them at a disadvantage.
The system was never implemented due to time constraints.

While the Project M Backroom was preparing the release for Project M Demo 2.5, a mod of Brawl that makes it play like Melee, they discovered that there was a bug in the game where button inputs can take anywhere between zero to two frames before being recognized by the game. This means that anytime you press any button in Super Smash Bros. Brawl, the attack might start up later. It is unknown why this happens.

The characters Dr. Mario, Roy, Mewtwo were supposed to make a return, and Dixie Kong, Plusle and Minun, Toon Zelda (Tetra), and Toon Sheik were supposed to appear as newcomers.

Files for these characters (sadly incomplete) can be found in the game's ISO.

Masahiro Sakurai left a picture of his cat in the ice area in the Pokemon Stadium 2 stage.

The texture of the Metroid assist trophy contains a sprite of EarthBound's Mr. Saturn. It can't be seen in-game, as it isn't mapped to the model.

The Announcer (who also voices crazy hand and master hand) is Pat Cashman, who was the announcer for "Bill Nye, The Science Guy". He even acted in some scenes in the show.

As of Super Smash Bros. Ultimate in 2018, Shadow the Hedgehog is the only third-party Assist Trophy to appear in every Super Smash Bros. game since the introduction of Assist Trophies in Super Smash Bros. Brawl in 2008.

As of Super Smash Bros. Ultimate in 2018, only three characters that started out as Assist Trophies became playable in future installments:

•Little Mac, an Assist Trophy in Brawl, then became playable in Super Smash Bros. for 3DS/Wii U
•Dark Samus, an Assist Trophy in Super Smash Bros. for 3DS/Wii U, then became playable in Ultimate
•Isabelle, an Assist Trophy in Super Smash Bros. for 3DS/Wii U, then became playable in Ultimate.

In 2023, a webpage on Nintendo of Japan's website was created to celebrate the 40th anniversary of the Family Computer. One of the subpages is a list of nearly every game published by Nintendo for the system, including those released exclusively for the Disk System peripheral. The only other known official list of Nintendo-published Famicom games available is the Chronicle in the Japanese version of Super Smash Bros. Brawl.

However, the Famicom 40th Anniversary subpage omits several games that were included in Brawl's Chronicle. These include:
• Popeye, as well as its spin-off titled Popeye no Eigo Asobi, likely due to licensing issues with King Features.
• Spartan X (released as Kung Fu outside of Japan), likely due to the game being a license, as it is based on the movie Wheels on Meals.
• Miho Nakayama's Tokimeki High School, likely due to the game heavily featuring real-life Japanese idol, Miho Nakayama.
• Ginga no Sannin, a port of the home computer game The Earth Fighter Rayieza by Enix. It is not known why this game was excluded from the list.
• All re-releases of standard Famicom games for the Disk System (such as Super Mario Bros., Tennis, and Mahjong). The Famicom cartridge re-release of The Legend of Zelda is also omitted.

In addition to these omissions, while the Chronicle lists Mike Tyson's Punch-Out!!, the Famicom 40th Anniversary subpage instead lists the original Gold Version released exclusively in Japan, which did not include Mike Tyson.

In the Japanese version, two games featured in the Nintendo Chronicle list are Jump Super Stars and Jump Ultimate Stars, a duology of Smash Bros.-styled fighting games released for the Nintendo DS that serve as crossovers between several Shonen Jump properties. Coincidentally, both games feature Goku from the Dragon Ball series, a highly-requested non-gaming character for the Smash Bros. series.