In the ''The Stratosphere'' level in Birdie's Treehouse, there is a warp zipper in the upper right-hand corner. It takes you to a secret area which tests your ability of jumping from cloud to cloud, and rewards you with two extra lives and numerous M's.
Read ''Another Secret Area'' first.
Elsewhere in the level ''Stratosphere,'' another zipper sends you to an otherwise inacessable platform with 2 1-up cards. If you collect them and go through the zipper mentioned in ''Another Secret Area,'' they'll be reset and you can re-collect them.
Hit the first squirrel with the top block on club house level 1-2. Continue forward and take a block from the stack of six blocks.
Stand underneath the spider and press B + Up when the spider is at its highest point. The block will hit the spider, bounce off the stump, and leave the screen. Repeat this to collect an unlimited number of hearts.