Well, I don't know if anyone has interest in making a new run for this game, but it seems this topic has been brought back from the dead for one reason or another.
So I will go ahead and share this peculiar glitch my brother has discovered some time ago:
http://www.mediafire.com/?3c3qrx13byoeucj
I hope this mupen video example will work for you guys. In case it somehow doesn't, I will attempt to give a step-by-step on how this glitch works just below.
Step 1: Once in the Space World drive near the hall to the Trophy Race Challenge located on the east side.
Step 2: Honk your horn to call T.T. near the Trophy Race hall.
Step 3: Keep calling him until you've got him, with you facing toward the main lobby, glitched into the west-outward corner of the hall.
Step 4: T.T. should be hovering all the way to the top of the wall boundaries. Once you end speaking with him, drive under where he's destined to land. You will then be launched very high into the air, with the direction depending on where you got slammed by T.T.
The goal here is to launch yourself behind the T.T. amulet door and straight to Wizpig 2 with no need to do any of the Space World races.
Also another discovery I've made is that you can get under the beach with the lighthouse in the main hub by doing a downward airplane loop. This allows you to go to Wizpig 1 immediately. Though that isn't of much use because you cannot go to the Space World without doing the Trophy Races first. You can also a similar trick at tracks such as Hot Top Volcano.