http://www.youtube.com/watch?v=Dtw8_K-x12c ARound 30 seconds in a preview of Innovention at Epcot starts showing Sonic 2 and what looks like some unreleased Virtual Reality hardware. Just thought this was pretty cool.
Not very much but the Sonic 2 level is one that made it to retail (if it wasn't apparent) though I'm not sure that font/style for the timer is retail.
I don't see any Sonic 2 in there, just Sonic 3. Edit: He beat me. The levels it shows are Azure Lake (competition level), Special Stage, and Launch Base Zone. I don't notice anything odd about the shots, so they're probably final. It also shows Toejam and Earl 2, Aladdin, Ecco, and some others I can't recognize.
And here is that scene in the final game. It's the Desert Palace level from the 2-player mode of Sonic 3 (the title bar says 'Sonic & Knuckles' because this screenshot was taken from Sonic 3 & Knuckles).