If you hold 1 and press D, you go to the Dream Over screen. I know one of my kids loved to play that screen. :)
If you hold 1 and press 3 (or is it hold 3 and press 1?), you will go to Act 3.
If you hold 1 and press 2 (or is it the reverse?), you will start near the beginning of the game.
There are others, but that's enough for now! Enjoy!