Sonic the Hedgehog 2 (16-bit)/Bugs
From Sonic Retro
Super Sonic at the end of a level
Attempting to transform into Super Sonic after hitting a signpost or prison capsule results in Sonic "walking" in mid air, and becoming unresponsive to controls. This doesn't cause the game to crash however, as the next level starts as normal after the score tally.
Fixed in: Final revision 02
Tails high score
This bug occurs in all known betas and prototypes; an easy way to reproduce it in the Wai beta is to go to Hidden Palace Zone, immediately spindash to the right, and press jump as Sonic dies.
In the final, Tails starts flying when Sonic dies, making him unable to hit enemies.
Fixed in: Final version