Facts

Sonic Megamix "V5.0B"

I actually have a rom of Sonic the Hedgehog Megamix V5.0B I won't post a link (because i'll probably get banned) but here's some screenshots.

WARNING:These will contain ALOT of spoilers!

The time attack menu music has a few additional notes sounding like birds.
Special Stages are very different as they are based off the Sonic the Hedgehog CD
The build was leaked in mid-2011.
Stealth uploaded a video.
Ending and Credits crashes (Credits does in original mode).
Stealth refers to it as "V5.0a"
City Outskirts CD theme reminds me of Studiopolis act 1.
Final Fight is Unfinished