Most people don't know any more than the producers/directors. Doesn't matter what the genre is, if there's a knowledgeable viewer, it just kinda blows the movie for them. Guns. Cars. Planes. Whatever.
Maybe not whatever. Imma guess the porn viewers don't complain much about inaccurate props.
Larry Vickers did a series about movie guns. The guys explain why certain guns are used sometimes, and why sometimes historical accuracy is abandoned. They're pretty interesting to watch.