Last month at the Game Developers Conference, Hirokazu Yasuhara (game designer) and Naoto Oshima (character designer) gave a talk about the history of creating Sonic and the original game. That talk has just been uploaded to the GDC Vault for free! There's a bunch of neat tidbits in here for fans and developers alike. Look at those dance animations that didn't make it into the game due to space limitations.
Check out the video here!