New Super Mario Bros. Easter eggs

Extra Super Mushroom
In world 1-2, the pipe one, before the secret exit there is a pipe that you can go down. Within this pipe is a red koopa. DO NOT USE YOUR FIRE FLOWER ON THIS KOOPA!! you have to jump on him or knock him from below. Once you have done this, kick his shell. you will notice that below the extra pipe it is knocking away at bricks. Through this bricked up passage is a whole lot of Goombas and a ? block with a super mushroom in it. if you destroy everything you get 2 lives. You can also do this with the Blue Koopa shell and you can do the run thing and do the same thing.