“Whenever possible, insert a detail of realism.
What do gun ‘silencers’ really do? How does the legal process really work in such-and-such a situation? Is sodium pentothal a real ‘truth serum’? If the film is of an ‘historical’ genre (like a Western), see if that one-scene character can be replaced with an actual real-life historical figure, without changing the facts about that figure.
Those ‘in the know’ will thank you for it.”