Continuity mistake: At the beginning of the movie Merlin says, "Show the sword" and we see Excalibur for the first time in a human hand. Uther at first holds the sword with his thumb wrapped around the handle, then in the close-up his thumb is pointing upward then in the next shot his thumb is wrapped around the handle again. (00:03:55)????
Continuity mistake: King Arthur's second horseman carries three extra jousting sticks as they ride to the far end of the field preparing for the joust. After the first charge Lancelot says, "You joust well, Sir, I offer you another lance" and King Arthur rides back to his second horseman who now only has one jousting stick. (00:48:15)????
Continuity mistake: We see Morgana for the first time as she stands in the back of the wedding and turns around to look at Merlin. The order of the guests in front of her does not change but the banners above their heads are entirely different as she approaches Merlin in the next shot. (01:00:45)????
Deliberate mistake: Lancelot says to King Arthur, "I sought only not to harm you" before he dismounts and they fight with swords under a tree. If you look closely at the tree there are no marks on it before they start fighting, King Arthur strikes one blow and as Lancelot pushes him away there are several marks on the bark of the tree. (00:49:30)????