Star Wars Episode 1: The Phantom Menace - Siths Sure Can Change Their Clothes Fast!
As Senator Palpatine is talking to Queen Amadala when they are descussing in-doors that with the Supreme Chancelor they have no action will be made quickly enough for the people of Naboo. Notice that the camera is focused on Senator Palpatine and he is wearing a blue alphet, then cuts to the Queen, then back to the Senator again and now his alphet is green, then it cuts again and stays blue. A very weird and obvious slip up, im surprised that even got by George Lucas...i always thought he'd be smarter then that.