Hop onto the pink polka-dot square at Point 1 and begin riding it right, across the level. Carefully stay near the right of the square as it rotates left and nearly pushes you up. Mario can hold on for a long time before slipping off the surface, but don’t push it. As soon as one of the square’s corners is pointing to the sky, jump to the other side to keep from falling off.
Hit the P Switch to reveal a bunch of blue coins. Gather as many as you can.
At Point 7 there is a red pipe high above the rail. Use the Propellerhead power-up to zip into the air. Then, just as you’re about to drop back down, bounce off the Flame Chomp and into the pipe. This leads to an alternate ending to the level, which unlocks the path to the World 2 Cannon!