There are rumblings of a possible beta Banjo Tooie map.

The small level is a green pipe, with a stream of water. The level clearly isn't one you would've been able to play at, since the pipe takes you to your death when you fall, but it is conceivable it is still in the game as a cut-scene. We're hoping to confirm it soon. Thanks to Coolboyman of our forums for pointing it out, as when we tried out the warp digit it crashed for us.