Invisible blocks are only solid on the bottom side before they're revealed. Wasn't too hard to thread the needle on my second attempt, after I knew where they were. Didn't even have to open the editor to check.
Literally the first thing I thought after entering that room was "Oh, functional platforms being used for aesthetic purposes. How do I break this?"
It's not the most egregious oversight. At least there's a pit nearby so you're not at the mercy of the clock. Still ruins the illusion of the level by making the upper level geometry visible, though.
Break all the levels!
I think it's easy to fix by making the toad house larger.