Ok, so it's not
that weird, but basically, whenever you're flying as the bat at the top of the screen, if you transform back into a human, you'll be rendered immobile in the same square in which you transformed.
If you wiggle enough, you can get out, but if you keep running to the right, you'll often be suddenly flung to the end of the stage in an instant. I think it's possible to get to the end of the long citadel stages in a few seconds like this.
Anyways, not a big deal, just a quirk. You know a platformer is legit when there's a random glitch hidden somewhere in the game :-).
Here's a short video showing both the wiggling and the stage-flinging in action (quality is mediocre/choppy, but visible nonetheless):
DivShare File - AVWW2.avi