The atmosphere and the sense of humor are both terrific. I have only found one ending so far, in easy mode - normal is a bit too much for me right now, since there are no savepoints in sight
Also, I found a void. Can't find the screen in the editor, so I'll explain it:
switch to normal difficulty, go up using the umbrella, then try going left, under the red cliff, again using the umbrella. Once you've moved to the next screen, try to return and there's a void.
UPD: Also,
when I attempted to replay using my save, it moved me straight to the ending. Was that intended? :(
UPD: One more void... normal mode, first screen with the bouncers, go left and then go back again. Maybe there's a whole row of warps missing?