Part 1 Roots: The Saga of An American Family - S1-E1
Other mistake: During the voyage aboard the Lord Ligonier, none of the African captives have shaved nor had haircuts during the long voyage across the sea, but they are clean-shaven and their hair the same length when they berth in Annapolis as when they were first loaded aboard ship in Africa.
Other mistake: As corvette guy races to get away from Ponch, the steering wheel breaks away, coming loose in his grip. Yet the car magically veers a sharp left before halting to a stop, instead crashing into the trees straight ahead of him.
Other mistake: When the throne in episode 5 & 6 is first introduced it is a normal throne or chair; it doesn't move when merely touched. But once the ceremony starts and after it's finished, it's suddenly a swivel chair. The base is never shown of course. But a swivel chair made of solid rock...?