When a person is knocked unconscious by a blow to the head, they will never suffer a concussion or brain damage. When they are alone, all foreigners prefer to speak English to each other. Seedy private detectives with drinking problems often have beautiful women with marital problems as clients. Driving in San Francisco routinely involves sailing through the air for hundreds of feet, so the cars sold there are built to withstand the subsequent landings in one piece and still be driveable. Even in the distant future, electrical panels in spacecraft will be highly prone to short circuits that produce showers of sparks at the slightest provocation.
All manholes emit steam.
Most men can smash any door down with their shoulder. Even before the advent of cellular phones, all psychotic killers had a way to place a phone call to their victim from inside the victim's house.