NOTE: To play the prototype in Kega Fusion v3.6 and up, the "Fast 32X Timing" option in the 32X configuration tab must be enabled. For older versions of Kega Fusion, a special release, which can play the prototype, was made available here(info) (268 kB).
Time Attack is much different in this one but still unplayable.
Player/monitor icons are finalized. They look like in the final now.
The US region title screen still says "Featuring Espio the Chameleon" unlike in the final version.
Knuckles and Espio still spin in the opening stage but Espio disappears.
The characters have a quicker acceleration in comparison to the final.
Pressing start during the tutorial will make the Dpad and buttons disappear.
Debug mode is enabled by default.
The HUD for powerups is not there.
You can choose your player before you return to the level hub from the intro level.
Instead of collecting Chaos Rings you collect Holy Rings.
It is possible to get a negative score.
Amazing arena does not change music once you hit the light switch.
There is the map of Newtrogic High Zone in the Sega screen.
There is a empty space in the character select screen.
Also, when you enter the world selection stages, the morning version of the world selection BGM plays, regardless of the time of day. If you exit, the band of stars that bind the two characters together will enlarge.
Mighty´s wallkick is also different from final. You can´t jump up, only for opposite direction.
The attraction picture in World Entrance spins.
In the intro, they got rid of Metal Sonic from the 111 proto, and replaced it with Robotnik repairing the Combi Capsule (or whatever the hell it is). Then Knuckles moves right to Espio, but you can run away from him if you run to the left of him.
Wechidna can no longer fly now unlike in 0111.
The World Entrance is incomplete, it also suffers from palette issues, deformation problems & the inability to select a stage.