Gun Goof
I just submitted a goof for the final battle, when Boss Wing had the shotgun.
He started out with a double-barreled "over-under" shotgun, but when he saw both twins he had a pump-action shotgun.
The double-barreled shotgun "breaks" to load it, and it holds one shell in each barrel. A pump-action shotgun has a magazine tube under the single barrel, and you "pump" it to eject a spent shell and load a new one. It typically holds 5-8 shells.
I always think it's interesting seeing gun goofs like that, in car terms it would be like driving a Ford Mustang, and then one shot changing it to a Chevy Camaro.