It's kind of hard to describe since I had like a few minutes to play the game but here's what I found when observing and playing the game.
- Mee Mee is confirmed. (She has AiAi's old car I think...with Pink and White decorating her vehicle)
- Two Items can be stored when racing. The second item appears beneath the first one and has a button prompt (B for the 360 version). Edit: In two player it seems (played with my bro on it)
- Knuckles' All Star is the Master Emerald emitting energy.
- Not sure if this was a glitch but I was sent back into the previous lap. I assume it was an item
- The Giant Robot Fish from Generations makes a splash after the Octopus Area
- Pre-set mines are also present on Seaside Hill
I unfortunately cannot give you any proof as I don't really bring cameras to film/take images of the game, but this is what is fresh from my mind anyway.
If Sumo can confirm this, it would mean I am not just seeing things. XD
The playable roster was only 12 or 13 characters...and I don't think Vyse or Gilius could be played but Ulala and Mee Mee definitely were.