The music in Fountain Of Dreams is an orchestral remix of the Gourmet Race theme from Kirby Super Star. This remix was used in Kirby: Nightmare in Dream Land during the battle against King Dedede, and has since been recognized as the fountain's theme. Kirby: Nightmare in Dream Land was most likely in development during the creation of Super Smash Bros. Melee, and so the fountain's music was added as a teaser for the upcoming GBA game.

DK's voice clip's were originally meant to be recycled from Donkey Kong 64, performed by Grant Kirkhope. But much like the original Super Smash Bros., it was decided giving DK a more realistic gorilla voice would better fit the game.

Although he appears to be a flat sprite, Mr. Game & Watch is actually a 3D model designed to look 2D from the perspective of the camera.

Giga Bowser was a playable character at some point in development, albeit likely only for testing. He can be made into a playable character using cheat codes, and the announcer will even say "Giga Bowser" when he is selected. All boss characters are playable in some form using the debug mode.

Some of the trophies have strange reflection textures:

• The Ayumi Tachibana trophy has a reflection of a heavily embossed cat's face.
• Fire Kirby has a reflection of an inverted baby face.
• The Ocarina of Time trophy has a small reflection of the sky.
• Multiple trophies use a screenshot of Osohe Castle from the cancelled EarthBound 64.

If Mr. Game & Watch absorbs 3 strong enough projectiles (Such as 3 fully charged PK Flashes) using oil panic and uses it against a shielding character, their shield will be broken, and Mr. Game & Watch will be sent flying back at extreme speeds. Unless there is a wall behind him to stop him, he will die almost instantly. This is known as the "Kamikaze Glitch".

Neither Roy nor Sheik appear as opponents or allies in Melee's Classic Mode (though Sheik can appear if Zelda transforms during battle). Ganondorf also cannot be fought, yet he can show up as an ally. Despite their absences, all three have their own intro poses programmed into the disc.

Among Plum's trophy's textures is a picture of a gun, which appears to be an AR platform rifle.

When on the stage, "Battlefield", in Classic, Adventure, and All-Star Modes, or in Event Matches "Space Travelers" and "Mewtwo Strikes!", it has a circular swirling rainbow design in the background. This background does not appear when the stage is selected normally in Versus Mode, and is otherwise unavailable.

Although Master Hand and Crazy Hand can't be outside of the stage Final Destination without glitches or hacking, their names will still appear correctly on the monitor of the Pokemon Stadium stage, albeit without spaces as "Masterhand" and "Crazyhand".

The information box for each trophy that states the game of origin includes different information in each region. The NTSC version includes a release date, the JP version states the system the game was released for, while the PAL version simply states the game of origin.

In the North American release, The Master Sword's trophy incorrectly states that it first appeared in The Legend of Zelda: Ocarina of Time. This was corrected in the PAL release, which correctly states that it came from The Legend of Zelda: A Link to the Past.

Setting the game's language to Japanese will cause Falco to say one of the two quotes when taunting:

- Falco's taunt #1: "Ore no emono ni te o dasu na!" ( 俺の獲物に手を出すな！, which is translated as "Do not dabble in my prey!" (or "Hands off my prey!" in Brawl onwards))
- Falco's taunt #2: "Nigasu ka yo!" (逃がすかよ！, meaning "Like I'll let you escape!")

However, when the game is set to English, he will simply scoff.

In the Japanese version, the Motion-Sensor Bomb is based on the Perfect Dark Proximity Mine. Although it was changed in the US version to remove all references to Perfect Dark, the game and it's developer, Rare are still mentioned in the credits. The design of the bomb was changed, though it resembles the design used in the original Smash Bros., which was itself based on the Goldeneye 007 Proximity Mine. The trophy description calls it "a favorite covert weapon of spies and other stealthy operatives.", and the game data only says "TOP SECRET".

The PAL version uses the same design as the US version, but renames it Proximity Mine, and the description mentions the Carrington Institute from Perfect Dark. However, the game is still listed as "TOP SECRET". This is despite the PAL version being released later than the other versions.

In the Onett stage, a hidden rice ball can be found behind the flower pots in front of the drugstore. This can be seen through camera hacks.

In the opening sequence to the game, there is a short moment where Fox - piloting his Arwing, crosses paths with Wolf in his Wolfen. A mugshot of the two characters in their cockpits is briefly seen. In early days of the game's release, this led to much speculation of Wolf playing a role in the game, perhaps as a playable character. However, this was not the case, but he would eventually become playable in the series' next installment Super Smash Bros. Brawl.

Ness' Yoyo says "Dolphin Loop. HalLab Nintendo 2001." on the front, a referencing the Gamecube's codename 'Dolphin'.

In earlier versions of the game, the lab in Termina: Great Bay could be entered from both sides, and characters could stand on top of it. This idea was eventually canned and the laboratory was closed and moved to the background. However, the lab still has some textures and models of some pipes inside of it, likely remnants from the initial idea.

In the Spanish version of Paper Mario: The Thousand-Year Door, one of Rawk Hawk's lines is slightly changed to "¡Los aficionadillos deberían quedarse en casa jugando Super Smash Bros. Melee!" (translation: "The weaklings should stay home playing Super Smash Bros. Melee!") after having defeated The Koopinator. In all other versions of the game "Super Smash Bros. Melee" is simply replaced with "video games".

A screenshot in Super Smash Bros. Melee's instruction booklet shows a Stamina match in which there are characters with more than 150HP. This could either mean that the original HP was a higher number, or that it was player-configurable.