Factual error: Towards the end of the movie, when Clint Eastwood is flying away from Russia, the Russian cruiser is really either an American Leahy or Belknap class cruiser.
Factual error: When flying towards the Russian missile cruiser, Gant says that "infra-red detection beams" have locked onto the Firefox. There is no such thing - infra-red (heat) sensors are entirely passive, meaning they do not give out any kind of signals and cannot be detected.
Chosen answer: There was just an explosion in the hangar and in the resulting confusion none of them were sure why it was moving. To get it away from the fire is not unreasonable. Also, the Soviet military is not big on showing initiative. Unless told to disable it, none of the guards would risk severe punishment for damaging a valuable aircraft.
Grumpy Scot