What bothers me more than the flubs and screw-ups in fictional shows are the ones in what are supposed to be history shows.
Today, with CGI there is no excuse for planes, tanks ships, etc that don't look right. But, they still do it. Not as bad as it used to be, but there are still mistakes, even in the CGI stuff.
Essentially, the only people working on the movie who actually know what is the right stuff are the tech advisors, and they are not infallible.
And, they are only advisors. The director gets what he wants, historically accurate, or not. Sometimes, reality is deliberately ignored for dramatic effect.
Other times, its a question of "this is the only way we can afford to do it", or, "we can't get the right stuff, this will have to do".
TV shows still lag behind, mostly because they are "low budget" compared to major studio movies, and getting stuff right is less important than getting it done. Also, by the time the show gets its final screening, it may be too late/too expensive to correct errors that only get discovered when the show is screened.
Someone really needs to talk to the sound editors (or directors who demand it). When they put in the click of a cocking hammer, or the sound of a racking slide where it doesn't belong, those of us who know better recognize it. The tech rep on the set would recognize it too, except they don't even know about it on the set, its added in post production...
Even CGI screws up, if the people doing it aren't gun or history buffs. One of my favorite subtle screw ups is in Enemy at the Gates, but only a panzer buff would recognize it. There's a shot in a German tank park, nice rows of CGI Panzer IIIs facing each other. The row of tanks on one side is perfect, the row opposite is a clear mirror image, easily seen (if you know what you are looking at) because the hull machineguns (right side of the real tank) are on the LEFT.
And, speaking of sound, this is the most common "gun flub" I see, overall, every action scene, people shooting without hearing protection, shooting rifles and pistols inside small enclosed spaces, and being able to hear not just normal conversation but small sounds and whispers immediately after the shooting stops.
I have been exposed to that kind of noise, and my experience was much different!!