This is REALLY odd! On World 5, Level 3 ("Wow, What an emormous tree!"), you will come to a gap with a button on the roof, which, when pressed, will activate a gust that splits you and takes you to your next destination. If you dont press the switch, you can jump out. If you go right you can climb up an invisible slope and then unsolid visible one. if you go left, you can take a massive fall to get to the ground and basically the bottom of the level.