Revisiting the off-screening of objects, it actually can go against the player in certain situations, such as the falling jet platforms in Flying Battery: I had an instance where I clipped off of one of them as well, right at the exact moment when it shifted from shaking to falling, so I thought "I'll just jump right before the transition happens" except that off-screens them entirely, causing me to fall to my death. I guess just increase the killzone to be a couple units past the screen instead of disappearing things immediately after they're not visible.
And speaking of Flying Battery, I wasn't a fan of how the last green switch in External In-flew-ences was placed over a pit, so you have to be to the left of the switch when you hit it in order to land on the platform. In retrospect, I think you intended for the player to see that shaft while going up the previous one, but in that case, you should put them closer together, maybe even only separated by a single-tile-wide column.
EDIT: Oh, and the blue rocket power could also use an explanation for how to use it since, just like the pink rock power, it also works differently from all the other powers and took me a minute of trial and error to figure out.
EDIT 2: It'd be nice if the coin trails in Very Long Fall didn't lead AWAY from the paintings, because that's another level where you can't really backtrack; the most you can do is go back to a checkpoint from the pause menu. I did appreciate how the level design at least lets you see that you missed it before you hit the next checkpoint, though.
EDIT 3: and speaking of Very Long Fall, I'd appreciate if you plugged up the hole in the lower-right. A previous Flying Battery level lets you duck in those thin tunnels from a jump just fine, but for that one, it never worked.