In the Hazy Maze and in the basement you will find doors that lead to hills with glass walls directly above them. Their purpose is to only allow you to go one way: down the hill. Use the following trick to go back up the hill. Step back from the hill about 15 feet, dash, and long jump (twice if possible) from 3 feet in front of the hill. Then, regular jump (also twice if possible), then dive (with A). After a few attempts you should be able to bypass the one way system.