One thing I can't help but see all the time is when someone walks to a group of people and singles one person out to talk and the pair say something like "give us the room" and everyone else leaves. Scenes similar to this happen all the time. Even in casual settings in movies. At some point I realized it's probably because it's easier to not have a second set for a private space just for a quick conversation. I can no longer unsee this.

No one knows how to hold or use a kitchen knife properly.

I'm a pilot. Sometimes screenwriters do a pretty good job with aircraft, sometimes they extremely don't. They'll show the wrong instrument when talking about a reading (a vertical speed indicator pointing to 200 feet/min climb over dialog that says "descending through 2,000 feet) or ATC will clear someone to turn to a heading of 540 or clear them to land on runway three niner, and don't get me started on aircraft engineering.

There's a scene in The World Is Not Enough where James Bond shoots a powered parachute in the wing and we hear engine struggling sounds.

My favorite has to come from the movie Iron Eagle. Near the beginning, Louis Gossett Jr is tinkering under the oil dipstick door on a Cessna 150, and the following dialog is exchanged:

"How come you're making my mixture so rich?"

"As lean as you were running, if you went into a stall you'da lost your engine and you'd never be able to pull it out."

What the Appalachian cousin fuck are you talking about, Louis?

Guy 1: Can you enhance that grainy camera picture so I can make out that license plate so I can read it? Even though the license plate is just two pixels in the original recording?

Guy 2: Sure. I'll just use this wondertech to... ah, there you go. One click did it.

Videogames and boardgames. Videogames are always depicted as the players wildly buttonmashing and getting into weird positiona for some reason.

Boardgames are not as common, but if they are they have glaring issues if they are made up or not played correctly if they aren't. The only pefect example of doing it right i know of is hokagou saigoro club, which uses real boardgames and explains them in detail. You can play some of those games without reading the rulebook if you watched the show or read the manga.

Medical dramas often have the xray films displayed upside-down or backwards, also chess boards are nearly always set up wrong with either the pices in the wrong places or the board turned 90°

It's super minor, but I think the ones that annoy me the most are when they're showing an off angle of someone talking, but their jaw doesn't match the words. Normally it's to show the responders face.

I'm in IT. It gets comical.

Helicopters that didn't produce much wind when people are nearby.

when someone is on a phone call on their mobile the screen is not showing the call screen.

Medical and psych. The beefy male orderlies in white tackling people. 10% of the time it’s like that, more so on a child or adolescent unit, but mostly it’s hey, let’s go talk over here about your feelings and come up with better choices and that works. Being heard, works. Most of the time, the orderlies wear street clothes. The shot is real but it goes in a muscle not the neck.

Stock sound effects are comically misused sometimes. I think my favorite was in one of the Schwarzenegger movies (True Lies?) a helicopter (with no wheels) lands kinda hard, and you hear a car-tires-screeching-to-a-halt sound.

Also not really an error, but once you recognize a stock sound effect, you'll start hearing it constantly. Like every single time someone sits down to eat, they make the exact same silverware-clanking-against-the-plate sound (especially in shows like Chopped - every time the judges go in for a bite, same clickety-clank.

Empty casings not being ejected from guns. It doesn't even need to be shown - just splice in a sound effect, FFS!