To me, if one is going to maintain the suspension of disbelief, you have to obey all the ordinary everyday rules that people know and understand. One can believe an massive alien invasion with giant biomechanoid floating death cannons, so long as the world rules beyond that are consistent. But if a human character, in avoiding one of these cannons, jumps off a ten storey building without any sort of aid, or interruptions to their fall, and land unharmed and run off - that's the deal breaker. One knows that's not possible, and suddenly one is left questioning that moment, and by default, the rest of the film.
I mentioned in a post yesterday that I hate it in films and tv when medics use the defibrillator paddles on a woman to try and restart her heart, and they are using them through material - bras, tank tops, etc. - rather than on bare skin. It pulls me right out of the moment, because I know it's not right.
I also mentioned hating when people can just break passwords when they have no information on the person, which has become really common in shows. Any computer whizz can break any password, within a relatively short time.
Another one I hate is when someone who is driving spends time looking at the their passenger rather than paying attention to the road. Quick glances are fine, but when they're maintaining eye contact for whole big chunks of conversation it annoys me. If you regularly did it in real life there's no way you wouldn't crash.
king_espresso mentioned that he hates when people don't wear ear protection on board military helicopters, which is a great one. Well, except now I'll be looking for it and getting annoyed by it.
kaths brought up the way people type madly on computer keyboards to do things that the rest of us would do with a mouse. We're in the internet age, everyone uses computers, we know they don't work this way.
kaths also mentioned the way they can zoom in on a small section of a photo, blow up that section, sharpen/clean it up, and suddenly have a incredibly clear and detailed picture. It's the equivalent of being able to blow up my icon for this post to read all the book titles.
So what about you? What regularly used, unrealistic film and tv conceits pull you out of the moment?