Revealing mistake: "Alan a Dale": Lady Mildred rides side-saddle. But when Gisburne gallops away with her, some shots reveal that the stunt woman riding the fast-moving horse is astride it full straddle. Her skirt is blown back just enough to see a brief glimpse of the stunt rider's real leg on the horse's right, and the fake pair of legs in side-saddle position on its left. For just a moment, the lady appears to have three legs.
Continuity mistake: "The Time of the Wolf": Robin slays his evil twin and leaves him on the grass near the standing stones. The body then changes positions without anyone touching it. When Robin leaves, its head is pointing to screen-right. But when Marion arrives, Evil Robin has done an about-face: his corpse is now pointing to the left.
Continuity mistake: "The Greatest Enemy": It's full daylight when Robin sends Marion and Much away and stays atop the crag to hold off the sheriff's men. The sky behind him is blue. But in the next moment, as he starts firing arrows at them, there's a setting sun behind him and the sky is red. In the following scenes, we see full daylight and blue skies again.
Continuity mistake: "Robin & the Sorcerer, Part 2": There are two arrows already on the target when Robin's splits one of them. When the target is carried back to the review stand, only the two splitting arrows are there (not even a hole in the cloth where the third should be), and those have somehow moved from the upper right sector of the bull's eye to its very center.
Revealing mistake: "Robin & the Sorcerer, Part 2": To rescue Marion, Robin kills the bad guy by stabbing him with the silver arrow. A few moments later, after much writhing and screaming, Robin pulls the arrow from the corpse. But its tip and shaft are perfectly clean. Not a drop of blood in sight.