In the editor, running a mission where a Me163 intercepts some B17s, I observed the Me163 'pop' in the air, presumably from a head shot. To my amusement the mission viewer continued to track an invisible Me163 through the air. Then, the clincher... The invisible 163 began lighting up a B17. In addition to the cannons firing, the little wheels from the 163 were jettisoned from the invisible plane as if they were bombs.
Having now observed this invisible plane phenomenon a few times and successfully recreating it a few times, and then tonight watching it happen in the editor, I am thoroughly convinced there is a bug in the off line mission logic that handles the head shot 'death' of AI controlled planes. The plane explodes and disappears, but the AI continues to fight an invisible plane.