An interesting Warp Zone note:

In Super Mario Brothers 2, the Japanese version (ie: not the version based on Doki Doki Panic), there are warp zones that take you not ahead, but backwards. At the end of several of the underground stages, you cleverly jump the bricks surrounding the pipe, where you find yourself with the only options being to either let time run out so that you perish, or go back to world 1. Either way, you feel like a complete moron, and some Japanese programmer has had yet another chuckle, at your expense.