If you watch close it flies out just after windu cuts it off, you can see the shadow of the head leave before the helmet hits the ground.

There was an episode of Orville that explored that very thing.

I was going to go one better with 'slammer' but ya beat me to it.

Im in act 3 and only encountered the "you're underleveled" message once at that same point. I havent scoured the areas for everything nor speed run the main story. I think act 1 is tight like you said, but it seems to be much looser as you progress.