Yeah that is true as well. They seem to be able to fly a little bit higher than you at the top of the screen. This for me is part of the tactics though, get on top of them before they reach the top of the screen.
Yeah, it's on purpose! Otherwise being on the sky would be too safe (as just tapping up there would let you win all matches) abd that's boring and static. The idea is to fly aorund and juke them!
I will however add smoke to all units that can fly over you (and not just "powered up" guys") so it's easier to tell! Next update, as i will add some fan characters as well!