The implication, I think, is that he thought she was 'filling in' for him - that is, since he hadn't been much of a presence on the streets, she was doing his job. As such, he thought saying 'I'm back, the streets aren't big enough for the two of us, and I don't like your M.O anyway - beat it' would be enough to send her packing. Kind of a dumb mistake, but then he realizes this later, and feels guilty about it.
As for the trajectory of the bullet, that'd be difficult to prove. The angles change around quite a bit during the sequence, and we never really get a feeling as to just where Panther IS - or at least, I don't.