So SWMBO has pointed out something to me and now I see it everywhere. Since I refuse to suffer alone I’m going to share this fascinating, infuriating tidbit with you…
Next time you watch a show, any show, pay attention to the drinks, especially the coffee cups. They are more often than not empty. You can tell by the way the actors move them around. I know this is for continuity and editing purposes but now that I see it I can’t unsee it.
You’re welcome. 
What else have you encountered that makes you crazy?
Flat soda pop and watery milkshakes.
I’ve noticed the coffee cup thing too.
Also, watch someone on television carry bags of groceries. They shift them around as if they weigh a few ounces.
Including the baguette or stalk of celery sticking out the top.
mmm
They sit down to a meal, but don’t eat anything.
I dont always believe there is someone on the other end of the phone call.
Gold bars weigh as much as candy bars.
Also, I see scenes all the time with two people in a bar, they order drinks, then decide to do something else and just walk out, leaving the drinks untouched. Not an emergency, just “hey, wanna blow this pop stand and go do (xyz)?” “Sounds great, let’s go!”
Street are usually wet, especially in older shows. They photograph better that way.
Sunny day in LA, and the street will be lightly wet.
Once you notice it, you’ll see it all the time. I just ruined TV for you. 
The coffee has long bugged me. I’d think they could weight them r something just so the actors would handle them more realistically.
I recall an earlier thread around here. I think the common assumption was just potential challenges related to spilling liquid.
Drinks in clear glasses, and clocks are pretty tough continuity challenges for TV/movies.
Cows don’t look like cows on film. You gotta use horses.
The coffee cup thing bugs me, too. Also, changing levels in clear drink containers. There’s a scene in a Seinfeld episode where a glass of wine sitting on a counter keeps changing, getting fuller and emptier during a scene. Now I’m always watching for it in everything.
Lots of continuity errors with props, clothing, and body positions between cuts in shows if you watch for them. For instance, look at the shadows on three cuts from this (brief) conversation in Cobra Kai season 4.
Sometimes, the actor starts talking before they’ve lifted the phone all the way up to their face.
And I can almost always tell when a show uses fake dinosaurs.
Women’s hair can also be quite challenging. Braids become looser, stray hairs escape, switch from behind/in front of shoulder…
My pet peeve is when characters enter a house or a room and don’t close the door. It happens all the time. People, anyone can come in! They can hear and see you!
My mother and older brother once got into a heated argument as to whether Dick van Dyke actually had coffee in his cup. (He did; I saw it too. Possibly the only time ever when this was true.)
In the MAD Magazine satire of The Fugitive, the final panel had Dr Richard Thimble wandering through a dark city where the “Making Streets Look Like It Just Rained Co.” was hard at work.
Women’s hair is almost never styled correctly in period TV shows like the Westerns and WWII dramas filmed in the '50s and '60s. Neither is men’s hair—MASH and Little House on the Prairie are good examples.
I read somewhere - here, probably - that people simply don’t notice contemporary hair styles. If characters have hair that, to them, looks “normal”, then it’ll look era-appropriate no matter when the story is set. I’m sure that’s still the case today: that plenty of “period” movies or TV shows from the past 5 years that we think look extremely accurate and well-researched now, will look ridiculous in 2032, at least in terms of hair and personal grooming.
That’s related to a problem on mine: people being heard talking in situations where they couldn’t be, and not being heard in situations where they had to be.
That one drives me crazy. A construction brick made of gold would weigh, what? … 40 pounds?