Sonic Jam (Game.com)
This game has a prerelease article
The Game.com Sonic Jam is not actually a port of the Saturn version, but rather just a collection of levels inspired by Sonic 2, Sonic 3, and Sonic & Knuckles mixed with bleepy music, ugly black-and-white graphics, inexcusable bugs, and an abysmal framerate.
- Extra Life - Press A, A, A, D, D while the game is paused.
- Invincibility - Press A, B, C, A while the game is paused.
Early versions of sprites for Knuckles are used instead of the final ones.
Graphics for an earlier version of Sonic & Knuckles, including the larger HUD that can be seen in pre-release material.
"No Lock On"
Presumably, Sonic & Knuckles would have had support for "locking-on" the Sonic 2 and Sonic 3 cartridges for new content, similar to the Saturn version. This would be the icon shown when playing Sonic & Knuckles by itself.
Leftovers From Other Games
Present at 0x1072D8 and 0x1078F2 are a female and male moan, respectively, from the Game.com version of Batman & Robin.
Present at 0x525CF is some text from the Game.com version of The Lost World: Jurassic Park.
A;B;C;D;E F;G;H;I;J 0;1;2;3;4 5;6;7;8;9 HARDING TEMBO AREA HUMVEE MOTORCYCLE CARGO CARRIER RV;MOBILE;LAB SNAGGER RV;3 STEGOSAURUS PACHYCEPHALOSAURUS TRICERATOPS PROCOMPSOGNATHUS VELOCIRAPTORS TYRANNOSAURUS;REX PTERODACTYLS
In Act 4 of Sonic & Knuckles, a couple of rings which were meant to be placed in a loop are shifted slightly to the right and up of their intended positions.