I came here for a good argument.
Well, do you want to have just one argument, or were you thinking of taking a course?
If you watch TV or movies, you see this with virtually any subject you could imagine. What it boils down to is that generally the people making the content need to dumb down everything to what Joe Average expects to see. If you've got greater-than-average knowledge of any field, chances are when you see people doing it on TV they're fucking something up.
We've already heard countless examples of computer GUIs. How about medicine? I was a paramedic, and my wife is an ER doc, and both of us cringe every time we see someone onscreen get a giant needle stabbed into their chest. Ever since Uma got the treatment in Pulp Fiction (maybe there were earlier ones, but that's the first time I remember seeing it) this is a great little dramatic moment that they love to stick into films and TV shows. In real life drugs go into a vein and even if the heart isn't going you can circulate with a little CPR. Jamming giant needles into the heart is just silly.
And while we're on the subject, all the CPR I see onscreen is shit. The last time I was certified was 2005 so I might be out of date, but last I checked we were at 30:2 compression/breath ratio at a rate of about 100 compressions per minute. Our memory aid was that we could compress to the tune of Queen's 'Another One Bites the Dust' (funny, I know) and that would get us pretty close. On TV it's way too slow, not to mention pretty rare that 30 seconds of CPR will magically revive someone without the addition of a defibrillator and lots of drugs.
I don't know dick about car repair, but I know what to do if I'm in a movie. I ask the hot chick on the side of the road to pop the hood, I stick my head in there, jiggle a few wires, then say, "Try it now." Then it'll start right up. Or possibly blow up, depending on the movie. Oh, and if you need to hotwire a car, you just yank that bundle of wires out from under the dash and tap a couple of them together until it sparks.
How about firearms? Again, I'm no expert, but I'm pretty sure when you shoot someone with a 9mm it won't knock them off their feet and throw their body 10 feet backwards through a plate glass window. But it sure looks nifty.
General electronics? It doesn't really matter what you're doing here; defusing a bomb, fixing a broken radio, breaking into a vault, etc. You just open up whatever device you're dealing with, connect a few jumpers with alligator clips on the end, clip another wire with a set of cutters and poof, you're golden. Just don't cut the green wire. Or was it the blue wire?
I'm sure most people could come up with similar things they see all the time, these are just a few of the ones that I notice. I probably gloss over lots more simply because for those subjects, I am the Joe Average and whatever they're doing looks totally plausible to me even though someone somewhere is gnashing their teeth over it.
When all else fails, read the instructions.