CPR. Doing 2-3 chest compressions, seconds apart, and then some mouth to mouth, followed by 2-3 more chest compressions. Or the needle into the heart thing. Or the shock a flatline thing. All of it. It's just all wrong.
On Andromeda? I believe it was, a villain used the stereotypical twist the head to break the neck and they fall over dead bit. The character proceeded to be not dead and did the stereotypical express their love while dying in the protagonist's arms bit, talking and moving their neck as if it wasn't broken. And then died.
Just several years ago I was shocked to learn that you do CPR if someone doesn't have a pulse, not a defibrillator.
It's a very, very common misconception.
Since then those portable defibrillator units have shown up in public places, which has led me to morbidly wonder two things:
Firstly, how often are they used incorrectly?
And secondly, how do you know when you're supposed to use it? I suspect the answer to this one is "the EMT on the phone will tell you to" but... IDK it would seem unlikely that most people could do something like that in an emergency.
Seeing a movie where they flip in a practice dummy and actually make me feel like they broke ribs to make it happen would be legit.
If the ribs aren't bending, ain't no way the heart is pumping!
Also having the CRP patient be absolutely trashed afterwards. If you're getting CPR, it's cause you dead, and they are trying to bring you back to life by beating life back into you. You were dead, then got probably the most painful beating of your life. The rest of the movie should be you recovering in a hospital.