On the "Through the Jundland Wastes" level, at the end where you can drive around in the little vehicles (you can only have one person doing this) go to the last part near obi-wans house and bring both vehicles to the ledge.

You'll notice that when you drive one the other follows. drive one of the side and jump off immediately.

If you did it right it floats in mid air and you can jump onto it.

When you're on it simply jump off the edge farther away from the ledge you started on and the other vehicle will push the one you're standing on and you will move away.

If you keep going you'll end up in a Grey area and you will be flying.

Remember not to press Y and sit in your vehicle because it will fall into a deep Abyss and you will die.