Oh, YEAH!
Yes, sometimes the Hollywood firearms technical advisors fall asleep on the job. We've all seen them: spent primers on ammmunition, blank cartridges in machine gun ammo belts, wrong pistols when the scene changes, etc.
I about chucked up my lunch when I recently examined an orginal 7mm Remington Rolling Block rifle at a gun show.
It came out of a movie studio that had used it in Mexican revolution/western movies for a couple of generations. The outside was in NRA Antique Excellent condition, and the bore was like new.
What was WRONG with the gun??? Someone had run pipe taps through the muzzle AND the chamber to prevent firing live ammunition (blanks only?), and taken a bench grinding wheel to remove a 1/4" from the barrel breech, receiver, breech block, hammer, and then tack-welded the hammer and block pins to the receiver!!!! Totally ruined and beyond restoration, and the price was still $350!!!!!
Sad!