If there is a cat in a mystery, it will jump out from under the furniture or yowl or both at the most suspenseful moment possible.
And while everybody is staring at Fluffy in relief, the real murderer will emerge from behind the curtains and strike.
The hero will get his man with the first shot. However, the villian’s first shot will always just miss, letting the hero duck and/or take retaliation (see KILL BILL v1, Vernita Green).
Fortunately, one person in a group of foreigners, from the Russian mafia to African mercenery soldiers to Japanese students, can speak broken but perfectly understandable English to the hero.
Women can all run like Marion Jones in stiletto heels.
Joe Random, you forgot about the leafy celery tops that also must stick out of the grocery bag.
In older movies, if a male wears his fedora with the brim pushed back on his head, he is a brilliant wisecracker with a heart of gold. A woman in a low cut dress with her hat worn low on her forehead, likewise.