There are many leaf piles here. Run through one to reveal a Super Mushroom or a Banana Peel. Once you get on top of the tree with the caterpillar creatures, an Invincibility Star may be found in one of the bushes on the left side of the treetop, but not on every lap. You may need to veer off to the left after hitting the bush, because the star pops out jumping left. This is useful in getting far ahead of the group if in first place, or to catch up as a bonus if near last place.
After going up the curved branch on the left (or the right if in Mirror mode), you will notice many piles of leaves and the caterpillar-like creatures. They may get in the way of this attempt, so avoid them at all cost. This may also require some luck. You must hit a certain pile on the left and a Star will pop out, giving you invincibility. It may only happen on the second lap, because it is difficult to find. Bananas and Speed Mushrooms can also be found throughout the entire course.