When the game was revealed during E3 2001, the game's introduction sequence was played, followed by gameplay footage demonstrating each character's movesets. The only changes made when adding this into the game was to the gameplay footage.

In the PAL version of the game, the Rainbow Cruise stage is renamed to "Rainbow Ride", likely for consistency with the international versions of Super Mario 64.

A segment of the remixed DK Rap used in the Kongo Jungle stage has the Character Select theme from the original Super Smash Bros. mixed into it.

In a prerelease build, the "Temple" stage originally had an elevator that led to the bottom of the stage, and had a fixed appearance. Players could also walk through the laboratory in Great Bay. Hyrule Temple had two mysterious platforms in the center of the stage. These platforms can also be seen in the game's Special Movie.

The last sentence of Pit's Trophy description reads, "Will Pit ever fight again?", possibly foreshadowing his role as a playable character in the next entry of Smash Bros. released 7 years later, Super Smash Bros. Brawl.

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. Despite the Mushroom Kingdom stage having a different design in Super Smash Bros. Melee, these signs still appear in the stage.

8-Player Smash (a mode introduced in Super Smash Bros. for Wii U) was originally planned for this game. However, due to technical performance, Sakurai stated "it was more than impossible."

The reflections found on the Fountain of Dreams and the models inside the magnifying glass when a character is offscreen are not actually the character's model, but rather a low res version of the model. These versions of the models don't show any item the character is holding, nor do their facial expression change.

Roy's belt buckle has the image of a lion on it. This is likely a reference to his endgame title of "Young Lion" in Fire Emblem: The Binding Blade. He was also referred to by this title in the Fire Emblem Awakening DLC.

If you turn off the music and select Captain Falcon on the character select screen, an extremely faint grunt obscured by the Announcer saying Captain Falcon's name can be heard. In the game's sound test, audio files can be found with "DEMO" attached at the end of them showing that every character in the game had similar planned sound effects on the character select screen, but only Captain Falcon's sound remains audible. Additionally, in the game's files, animations labeled "Select" and "SelectWait" can be found for every character in the game, many of which were either ripped directly from Super Smash Bros., are unfinished, or were repurposed in the final game. These are all presumably remnants of an earlier version of the character select screen that more closely resembled Super Smash Bros., where the character's in-game models were visible and used special animations and sound effects when selected.

There are nine unused event match character tags stored in the game's files. The unused character tags are for Peach, Roy, Pikachu, Pichu, Ice Climbers, Zelda/Sheik, Mewtwo, Ganondorf, and Dr. Mario. They are never seen in game because none of the event matches force you to specifically play those characters.

In an animated trailer for Boktai: The Sun Is In Your Hands!, a boy can be heard playing Super Smash Bros. Melee on a Nintendo Gamecube.

While almost every character requires eight frames after grabbing onto a ledge before they can do anything, Link is the only character that requires four frames before performing another action.

When the game was rereleased under the "Player's Choice" banner in the US, the color of the game's title on the spine was inverted.

In the game's files is an unused sound for when you get a Rare Trophy. This sound would later be used in Brawl, and as part of the character unlock screen in the subsequent three installments following said game.

There is an unused sound of the Boo's laugh from Super Mario 64 with the file name ST_GREATBAY_TKLE_LAUGH which would've likely been used for Tingle at the Great Bay stage.

As of 2024, Super Smash Bros. Melee is the only game in the series to not have unique introduction for characters in a VS. match, with every character spawning into the match as trophies. Despite having a timer counting down from three on-screen, it also doesn't have the announcer counting down from three to start a match, instead saying "Ready…GO!"

King K. Rool's render pose in Super Smash Bros. Ultimate seems to be lifted from an unused character select screen render for Zelda in Super Smash Bros. Melee.

Despite the English version of Melee using Star Fox Adventures' voice cast in the game's Corneria and Venom stages, the Japanese version uses all of the original Star Fox 64 voice actors. Shinobu Satouchi, Hisao Egawa, Kyoko Tongu and Tomohisa Aso all reprise their roles as Fox, Falco, Slippy and Peppy respectively. The former two's voice clips are also used for Fox and Falco as fighters even abroad.

Both Mach Rider's identity and gender are ambiguous. In the original game, the Mach Rider is portrayed with a masculine muscular build. The NES and Famicom manuals constantly refer to the Mach Rider by name ("the Mach Rider") or as "you" from the player's perspective, and do not use specific pronouns throughout, though the NES manual does at one point break from this to call Mach Rider a "he". However, the arcade port Vs. Mach Rider's stage clear screens slowly introduce piece-by-piece an image of a skimpily-dressed woman (bearing similarities to Jane Fonda's appearance in the 1968 film Barbarella) holding a dagger. It has never been specified if this character is the Mach Rider and is meant to be a twist reveal in a similar vein to Samus from Metroid, or if this is one of the other wasteland survivors. Years later, Mach Rider's trophy description in both the English and Japanese versions of Super Smash Bros. Melee years use he/his as pronouns. Even later on, Captain Rainbow, a Japan-only game centered around obscure and neglected Nintendo heroes, has an unused model for the Mach Rider being depicted with a skinny feminine waist, while not having visible breasts due to wearing armor.