If the hero/heroine is walking/creeping through a dark house/building alone and is hit/jumped on by the villain of the piece, they'll lose their grip on whatever weapon/torch they were carrying and it'll skid along the floor. This'll usually result in a scramble/grappling contest toward said item, though sometimes it gets 'forgotten' about while a fight breaks out then, at the last moment, the hero/heroine will recover it and use it.
Both villains and heroes/heroines have one shot knockout punches until they fight each other.
If the police go into a suspects house and it's dark, they won't bother with the lights unless they don't work. This'll also happen in dark houses during the day, when the police/whoever won't open the curtains/blinds, but instead walk around with a torch.