A nice hack that showcases many glitches. Most levels are consistent enough so that you can figure out a glitch even if you didn't know it. (And they're breakproof enough so that you'll find the intended solution first.)
The coin and moon placement helps a lot in figuring out where a glitch might occur. The 'OFF' blocks (see screenshot 7) that exhaust the blue p-switch timer save a lot of waiting time.