You could use the above idea ^ in the scene where Mace comes to arrest Palpatine.
He could be ordering food to the office. We could hear just the end of the kid from Domino's on the phone saying "How many chicken wings is that again sir...?" and Palpatine says "Order 66". Then Mace interupts.
But you could use that gag in several places whenever an underling asks Palpatine anything. Use the flower scene from the Room "A dozen red roses"... "No, order 66" etc etc