Suppressors are safety equipment, not badass silencers that let assassins shoot in near total quiet. But because the public only knows the movies, if you want to get a suppressor for your gun you need to pay 200 dollars. Imagine if we made it so you had to pay money to buy a muffler for your car, because Hollywood kept having cars with mufflers running dead quiet.
Or another one is bullet lethality. Handgun bullets make tiny holes in things without a lot of punch, so there is virtually no chance a single bullet from a pistol is going to knock a bad guy down. Maybe if you get very lucky and nail him in the precise right spot in the spine or brain, but otherwise he's still going to be alive and fighting for minutes or even hours. The police aren't putting 15 rounds into a suspect because they're dicks (well, they might be dicks I dunno) but because handgun bullets aren't very good at stopping people. You can only rely on volume of fire and hope you get a good shot to the central nervous system. Heck, even if you annihilate someone's heart the guy's still got about 10 seconds (called the 'dead man's ten') of useful oxygenated blood to work with before he's incapacitated - more then enough time for him to raise his gun and take you with him.
https://www.youtube.com/watch?v=msX4oAXpvUE
Computer/Hacker Movie inspired GUI: http://geektyper.com/
It used to be very annoying to watch certain parts of movies when I was younger. Computers and the internet were treated so haphazardly, it was cause for celebration whenever a contemporary computer interface was shown that wasn't entirely bullshit. This isn't relegated to just these topics, I assume there's a wide swath of annoying Hollywood misrepresentations on topics where there's a sizable subculture, and interest enough to sometimes be included in popular media, but with enough obscurity to the general public that Hollywood can basically make up whatever they want about it and most people won't know any better. For example, I imagine a good majority of car chases and slides around turns probably look like crap to stunt and race drivers, professional and amateur.
The effects of this range fro harmless to possibly shifting popular consensus in harmful directions (I could argue that a lot of early fear regarding the internet was misplaced, and the expectations of the public were so off that it may have retarded some basic security awareness for some time).
The annoying part is that all too often it's just a small matter of knowledge that keeps the representation from matching reality, and the only thing that stopped it from happening was a lack of care on the director's part for the subject they were representing. That's what the real shame is, because how hard is it for a director to get someone to sit in and consult on those topics?