In the Lessons Mode, under Chain Reactions #8, right next to Toad there is a green bomb next to two green Fuzzes in a row. According to the rules of Wario's Woods, the green bomb should clear the row of green things. But, when you start the lesson, the bomb doesn't explode! When you press X to start the chain reaction, the green bomb Toad was holding drops, and the row of green stuff is finally cleared.