Warp Wistles
1-3 - Kneel on white block towards end until you fall through.  Run to the right 
behind the "black thing" to enter the rom with it.

1 Fortress
-At the part with the door leading to the next room, fly up above
the ceiling to yuor right and you will fall in a pit with the warp wistle.

2 Fire Bros.
-Use the hammer on the rock in the upper right hand corner to get to a Fire
Bros. which holds the wistle.