The Sonic 3 prototype is rather well known for having many abilities that didn't make it into the final; of course, the most infamous of these is the proto-"Drop Dash" you can perform in-game, but there are also two unused abilities that can only be accessed through hacking. Silver Sonic 1992 covered both of them in the video below, but I will summarize them both here as well:

• The first of these abilities is a multidirectional air dash,…

Theory on Unused Sonic 3 Abilities (and Other Things)