The Pokemon, Ditto, was meant to be a possible helper when a Pokeball was thrown. He was supposed to transform into the player that threw the ball and would help fight. However, there were problems with its programming and it was removed. By using an action replay, Ditto can be put back into the game, but he is lacking his "transform" ability. Instead, all it does is say "Meta!" (it's Japanese name being Metamon) and disappears. Anyone who runs into it is dealt 7-8% damage.

Captain Falcons' red palette swap resembling Blood Falcon was originally planned to say "Hell Hawk" on the back, much like in Japanese versions of F-Zero games.

The Metroid trophy has an image reflecting off of its shell. The image is of the space station from the beginning of Super Metroid.

Luigi's voice is just a pitch-altered version of Mario's.

In Captain Falcon's "break the target" room, a picture of dolphins can be found on the left-most wall. This may be a reference to the original codename of the Gamecube, which was "The Dolphin".

In Luigi's "Break the Targets" room, the small square in the middle of the stage, which he begins standing on, is actually a Nintendo Gamecube.

There's a reflection of the 'Yoshi's Island' stage on the Metal Mario trophy.

There is a glitch that allows the game to advance to the stage selection screen without properly configuring the match. Any player that does not select a character will be set to Master Hand as a default. However, Master Hand will only respond to controller port 3.

An Excitebike racer from the game Excitebike, Balloon Fighter from the game Balloon Fight, Urban Champion from Urban Champion and Bubbles from Clu Clu Land were considered for characters that could be used to represent the NES era of Nintendo in the game, but Sakurai decided that the Ice Climbers from Ice Climber would be far more fitting as fighters.

The Letters "2L84ME" (too late for me) are printed on the back of the Barrel Cannon Trophy.

Unused character intro loading screens for All-Star mode can be found by using the game's debug mode. They were most likely removed because the player may fight multiple opponents simultaneously in some rounds.

There are many Regional differences between the Japanese and U.S. versions of Super Smash Bros. Melee. They include name changes (Jigglypuff is named Purin and Bowser is named Koopa in the Japanese version), event names ("Time for a Check Up" is "Don't Hog The Spotlight, Bro" in Japan), and different names for items (Bob-Omb is Bomb Soldier in Japan).

The main character of the game Devil World, Tamagon, appeared as a trophy in the Japanese version of Super Smash Bros. Melee. Tamagon was removed in the American version of the game but the trophy can still be found with Action Replay, complete with a translated description. Stranger still, the Tamagon trophy was removed outright from the European version of the game and cannot even be found with a cheat device, despite the fact that Devil World was released in European countries.

In early versions of the game, the Princess Daisy trophy contains a third eye beneath her hair if viewed at the right angle. In fact, there are many hidden eyes all over her head, but this is the only abnormal eye that can be seen in normal play.

Hideo Kojima had requested that Metal Gear Solid's Solid Snake be in the game, but due to time constraints he couldn't be added to the game's roster. Sonic the Hedgehog also nearly made it into the game. Sonic's creator Yuji Naka stated that Sonic was going to be in Melee, but he also was cut due to time constraints. Both characters later made it into the sequel, Super Smash Bros. Brawl.

In a March 2002 Nintendo Dream questionnaire with Mitsuaki Hagishima (the general manager of Nintendo's Planning Department), it was revealed that Banjo & Kazooie were planned to be included in Super Smash Bros. Melee as trophies. However, time constraints and the complexity of the approval process (as Rare, the developers of the Banjo-Kazooie IP, were situated in the UK) led to this being dropped, as well as other Rare associated characters (such as Joanna Dark from Perfect Dark) not appearing in the final game. This was brought up again in a September 2009 issue of Rare's Scribes, where it was mentioned that a lot of Rare character trophies were planned to be included in Melee, but it never happened.

Ganondorf's design in Super Smash Bros. Melee is based on his appearance in the Spaceworld 2000 tech demo which showcased a fight with Link and himself where he wields a large sword. This large sword only ever appeared in that tech demo and in one of his win animations in Melee. This specific sword would not be used in Ganondorf's moveset until the release of Super Smash Bros. Ultimate in 2018, where his design is based on that same Spaceworld 2000 tech demo as well as elements from his appearance in The Legend of Zelda: Ocarina of Time.

Starting in April of 2002, the FAQ section of the official website had the question "Are Sonic and Knuckles in the game?".

This was in response to the April 2002 issue of EGM, which jokingly stated that Sonic and Tails could be unlocked by defeating 20 or more Wireframes in Cruel Melee.

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.

The characters of Captain Falcon, Pichu, Ganondorf, Peach, Jigglypuff, Link, Samus, and Donkey Kong actually have two taunts; one for each direction they are facing (right or left). However, some characters like Donkey Kong, Samus, and Ganondorf have taunts that look identical but actually have very subtle differences that are hard to spot at first glance.