In the case of BTTF III, I can somewhat forgive it because they did show Marty being hesitant to fire a real gun at first, with his first shot going wildly over the gallery. I always sort of viewed that as, once he fired that first round and knew what to expect, he then turned around and was able to be a 'Crack Shot'. Still a bit of a stretch, but not as big of a leap as in some other cases.
Yes, there's at least some nuance there for suspension of disbelief. Unlike Rae who picks up a light saber for the first time and beats a Sith Lord. All that said, I'm pretty sure if you can play video games you can control drone strikes in the military.