People never take off their shoes or boots at the door even though they've come in from the rain or snow and/or tramped across muddy fields.

There's always dodgy dudes sitting on the steps of those NYC apartment blocks.

An empty taxi always appear as soon as the hero/heroine hails one.

Camera ground shots of car wheels going through a puddle are mandatory.

Nobody smokes the last half of a cigarette (unless they are a tramp or bum).

All commanding officers are clueless buffoons unless the part is played by John Wayne.