The 510 Palmtree Panic zone is the only zone to feature the 3 missing powerups, Blue ring, Super, and Timer monitors in the present. Some appear later on in pasts and futures of later levels.

This section is not found in the final version. It involves a floating platform going from side to side while being hidden by a pixelated piece of foreground.

The tunnels in the game do not work like they're meant to. Sonic does not automatically go into a ball when he enters, and Sonic can easily walk around in them. The only look which works effectively is the one which has a loop-de-loop underground, which you are forced to go around at maximum speed.

This tree trunk object seems to have been stuck in the side of the ground, with no real purpose. Perhaps it was originally going to be an entry or exit for a hidden tube warp.

In the prototype, this animation is displayed while running up the slope.

If you hit the spring to the left at the beginning of each act, Sonic will thrust forward without the camera following him. It will re-attach itself to his position as soon as he leaves the screen.

The first boss of the game is very different from the final version. This version is entirely grey, while the final version has a lot of red in it's joints. The feet are much flatter then the final, and most obviously is the large pincers Eggman has on the robot. They are replaced with bumpers in the final, but both versions act the same.

For comparisons sake, this is the final Eggman design.