Luigi's ability to have a higher jump but less trackion was actually from the JP version this is interesting because the USA release which was a reskin of Doki Doki Panic luigi replaced the 2nd character which had the same abilities.

In 2001 an updated USA All-Stars version was released on the GBA under the name Super Mario Advance which contains the following differences.

1. The palette is brighter because while the GBA can display SNES colors there's no back lit screen.

2. The charcter select was completely redone.

3. An updated version of (Not Super) Mario Bros was included.

4. Some layouts were changed/altered.

5. Red coins were added.

Also when Doki Doki Panic became SMB2 (SMBUSA) the game recieved some graphical updates.

Sonic 4 EP1 Boss Theme was actually from an early prototype of Sonic 3D Blast

Sonic 4

https://www.youtube.com/watch?v=cGOh3loQ6cM

Sonic 3D Blast 825 Prototype

https://www.youtube.com/watch?v=Te8RveELSpg

The Big Arms boss from Sonic Generations 3DS originaly used the Doomsday Zone theme instead of the Sonic 3&K Final Boss theme

The First Boss In Sonic CD is called the EGG-HVC-001.

The Last part HVC-001 is the Code name for the Famicon

Sonic's Top Speed animation from Sonic Mania is a reference to Sonic 2 Beta.

The Theme for Sunset Park Act 3 from Sonic Triple Trouble is a lower pitch version of an unused theme from Sonic Chaos

Sonic the Hedgehog CD prototype 510, referred to as CD Sonic the Hedgehog on the title screen, is the earliest known prototype of the game Sonic the Hedgehog CD for Mega CD produced on May 10th, 1992. This prototype features a prominent "Comin' Soon" screen. It was 'discovered' by a group of fans called Sega Extreme in the summer of 2000. The game contains all the stages of the final game, but in a normal playthrough the player can only play the first three: Palmtree Panic, Collision Chaos and Tidal Tempest. The rest can be viewed through the Level Select. This prototype contains several differences from the final game.

Sonic Retro Page

info.sonicretro.org/Sonic_the_Hedgehog_CD_(prototype_510)

How would you like a Doomsday Zone animation?