There was a mistake in ROTS. When Palpatine is fighting Mace Windu there is a shot where you can see Anakin's lightsaber hilt in Palpatine's hand instead of the Sidious lightsaber.
Did you know that the Sith title of Darth in fact predates the Sith? It originated in the ancient Rakatan language. The Rakatans were a species who ruled the galaxy in an ancient Empire thousands of years before the Jedi and the Sith. They were ruthless and powerful in the dark side of the Force. Darth meant one who defeats death.
