You know that trope where the action scene is on the roof of a tall building and then a helicopter unexpectedly pops up from just out of view? A helicopter hovering 20m away would be really fucking obvious, even if you couldn't see it. Just saying.
@mattb Everyone in action movies is partially deaf and have blown out sense of smell. They can't even tell a gun was fired in a room a few seconds earlier... the smell of spent gunpowder would be intense!