At the end of level 1-3 before you go to the black screen you'll find a bunch of blocks in the air. Find the white one and hold DOWN. When you fall through, run to the end and press UP. Hurry! If you do this correctly you will be in a secret room. Open the chest to get a whistle with special powers!

In the miniature castle of world 1 get the P-Wing and keep flying. At the top you should go over a wall and stop moving. Press UP to reveal another whistle!

You can also get this whistle by using a racoon suit. First take out the bone turtle, then go to the far right, start to speed up using the b button. When you reach the left end (your flying power should be full)start flying upward until you enter the secret room containing the whistle.

The 3rd Secret Whistle is in World 2. Beat a Wandering Hammer Brother and you'll get a music box or a hammer. Use the hammer in the Top right area in the Desert (not the level) by the Pyramid it is all the way North of it. Use the hammer there. You'll find a Wandering Fire Brother with the whistle along with a Toad's House with a Frog Suit in it.