Use the whip to loosen the stone ball from the wall in the bonus level. Go down and walk through the hall of snakes again. Climb over the large wall again, jump to the edge where the stone ball previously located. Push the switches to the right in the following order: 4, 5, 3, 1, 2. If done correctly, a door will open and a scene from Close Encounters Of The Third Kind will appear. Look out of the windows to see a UFO.