New Super Mario Bros.
Nintendo DS Cameos
Classic Mario Design
When you have completed all of the levels in the game, a Mushroom House appears in World 1 where you can buy custom backgrounds for the touch screen. One design can't be purchased until you have collected all of the Star Coins in the game, which features 8-bit sprites from the original Super Mario Bros.
Submitted by Fryguy64
Classic Mario Loading Screen
When the multiplayer game is loading, the loading screen features classic 8-bit Mario and Peach from Super Mario Bros.
Peach releases Super Mushrooms and Goombas that make Mario grow and shrink accordingly. Sometimes she will send two Super Mushrooms in a row, making Mario huge.
Submitted by Fryguy64