The first thing that I thought of were Hollywood style car chases. Obviously car chases are a real thing but I have never seen one that even remotely resembles anything like is in a typical action movie.
ETA: I’m not thinking of sci-fi tropes like time travel or faster than light travel.
People falling off a building or cliff and managing to hold on with just one hand, ultimately being able to pull themselves back up or having their friend pull them up by one hand. The number of people who could save themselves, or save someone else in this manner, is vanishingly small.
Shootouts. Specifically cop/criminal shootouts. I know that most cop shows would be pretty dull if there wasn’t a fair amount of fisticuffs and gunplay, but from what I understand, your average season of a cop show far outstrips your average cop’s use of his gun in his entire career, much less a year or two of it.
Plus, that stuff makes the news, and it’s just not that common. If it was TV show common, it wouldn’t be news, much less front page news on every station.
My son and I will often lampoon movie-isms that no one in real life ever does.
My favorite is leaving a room, but pausing halfway through the doorway, turning back and tilting the head meaningfully. Then repeating the last thing you said… for… emphasis.
“Well…” [open door] “I guess that’s just the way the cookie crumbles!”
[exit, but think better of it] [swivel, tilt head, meaningful stare]
[get serious]
“The cookie… crumbles.”
Doctors who sit by the patient’s bedside waiting for the family, or informing the family of a death or serious illness in the parking lot, or a crowded hallway.
p.s. For that matter, pharmacists who wear those Nehru jacket things.
Silver Spoons - S1 E7 - “The Great Computer Caper”
Ricky hacks into a secret military computer site and ends up getting into trouble. Very unrealistic for obvious reasons, as for the time this was basically unheard of.
Not so much nowadays, but neighbours just walking in to the house, unannounced, used to be common on TV. Howard Borden would walk into Bob Newhart’s apartment; Marcy and Steve or Jefferson would walk into the Bundy family home on “Married with Children”; and Larry would walk into Jack, Janet, and Chrissy’s (or whoever replaced her) apartment on “Three’s Company.” Nobody knocked or rang the bell, and the door was always unlocked.
No matter how urgent, or non-urgent, the matter is, my neighbours have never tried to just walk into my house or apartment.
IIRC, there was a scene in Dragnet where Joe Friday said something to the effect of, “In my career, I’ve pulled my gun twice and fired it once.” Or something like that.
The concept of a lone-wolf solo commando operative who infiltrates somewhere and kills a bunch of people all by himself. This is basically unheard of in real life, as any such people are trained to work as a team.