Sonic the Hedgehog 3 Beta - Angel Island Zone

The beta version of Sonic 3 uses sprites from Sonic 2 for Sonic and Tails. Also, the level layout is slightly different in this screenshot. The collapsing ledge is further back in the beta.

Similarly, this screenshot has odd-looking sprites. The sprites used appear to be from Sonic 2. The background is also slightly different.

When Knuckles comes on the screen, the letters (which are normally yellow) turn green. It's Knuckles' shoes which cause the problem. The final version doesn't display the SCORE/TIME/RINGS until Knuckles disappears, and his shoes are yellow instead of green. Also, Sonic's sprite is the proper Sonic 3 sprite, so this must be a later version. The position of the screen is different too.

Sonic's sprite is from Sonic 2.