8. John McTiernan - Die Hard
The Plot Hole: Hans Gruber's (Alan Rickman) techie Theo (Clarence Gilyard) drives an ambulance out of their operations truck at the end of the movie, but a glimpse inside the truck near the start of the film showed that there was no ambulance inside, nor any room to fit one. Where the hell did it come from, then?
Director John McTiernan admitted the mistake in a commentary for the film, and it was apparently a result of the movie's ending not being finalised before shooting began, leading to this hilariously basic continuity error that makes no sense at all.
At least the rest of the movie is so ludicrously entertaining that such flagrant sloppiness is surprisingly easy to forgive.