Skull raft doesn't fall off of the screen. It causes some serious bugs to have a moving object press up against a wall like it does here (see also, conveyer belts). Make it fall down a hole.
The section with the yellow yoshi feels off. At first I thought you had to get the yellow yoshi and the player could get trapped, but it looks like they can get through as long as they have SOME yoshi, which I suppose is okay. The switches have weird hit detection. You can't trigger them from above, even though previous coins worked that way. And with the blue shell there you don't even have to complete the bridge. I might give this section another pass.
The ? veggies in the bubbles looks like a mistake. They don't randomize until the bubble is popped. I'd probably just pick what you want them to be. Or maybe make them all throwable yoshi eggs, for the YI theme.
I kind of think having a pit at the end of section 3 is a bit much. It can already be pretty hard to get through it with all the turtles, and then it's easy to miss the coin trail at the end (which can get you a bonzai bill to the face).
The hit detection on the turtles feels off. Are these sprites really that much bigger than normal? I feel like I miss them with Yoshi even though I'm right on them.