When Will Varner drives through town in the ambulance, he covers some of the same distance and drives past the same parked car twice.
When Orson Welles arrives home for the first time, he is greeted by Lee Remick. In a shot showing the back of Remick's head, her hair is loose and uncombed. In the next shot, her hair is perfectly arranged.
Ben's room is on the other side of the house, but when he drags his mattress out onto the balcony, he's right next door.
When Jody locks Will in the barn to set it on fire, the fire has started before he has struck the match.
When Varner sees Jody digging in the yard looking for so called treasures, Jody hands him a silver dollar and Will says it was minted in 1910. No silver dollars were minted between 1904 and 1921. The coin Ben showed him while at gunpoint was likely a $5 gold piece but Will is holding what looks like a silver dollar.
When Clara tells Ben off at the picnic, there is smoke wafting through the shot, apparently from cigarettes or cigars smoked by the director and/or crew.
Orson Welles never knew how to drive. In all scenes of him supposedly driving, it can be seen that it's a much thinner stunt double.