I found a bug with the undo button. If you push a block into a hole and then undo, the block stays there. It may actually be a bug with the disappearing platforms, because undoing a move after moving off of one causes weird things to happen. I haven't tested if it's always the case, or only if you move off a disappearing platform and push a block into a hole at the same time.
Edit: It's definitely only when both things happen at the same time. The undo button brings back the platform fine if it's just disappeared, and pulls the box out of the hole if you just pushed it in, except when it tries to do both at once.
Edit 2: This is a very elusive glitch. I only noticed it a couple of times and I don't remember where, but now when I try to replicate it, it won't happen again. Basically the player block would end up in midair where the removed platform was, but it wouldn't come back, and sometimes a block that had landed in a hole wouldn't come out. You can have a hunt if you'd like, but I can't figure out anything more.