In the Hazy Maze and the basement you will encounter doors that lead to hills with glass walls directly above them that are meant to only allow you to go one way, which is down the hill. 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) to bypass the one way system.