Revealing mistake: The paving slab Broomhilda falls onto and supposedly breaks is already broken.
Continuity mistake: During the opening, the amount of flame changes on the wide shots of the frontmost house.
Revealing mistake: You can see that a huge rectangular hole has been cut into the ceiling of Latrines boudoir and filled in with balsa wood for when Rottingham gets catapulted through.
Continuity mistake: Marian has her crown straight, close to her forehead, but during her conversation with Robin it falls off and she puts it close to the nape of the neck. A split second afterwards her shadow is seen through the blanket and the crown is back on the forehead (as we confirm when she walks away).
Continuity mistake: When the horse moves under the balcony for Broomhilda to drop down on, we see the horse standing in the middle of a dirt area. When Broomhilda jumps, the horse moves to its left and Broomhilda lands on the sidewalk, but the horse was not standing on the sidewalk in the first place.
Revealing mistake: At the start when the fire arrows are hitting the hay roofs, you can clearly see wet patches of petrol or kerosene on the roofs, so that the fire can ignite quickly.
Continuity mistake: When Maid Marian is in the tub singing, her hair style changes as the view of her face does. For example, as she is singing straight into the camera, her curly hair hangs around her face with just a tiny bit pulled back on the sides; when the shot changes to a side view of her singing the hair has been pulled away almost completely from her face.
Visible crew/equipment: When the Sheriff of Rottingham is hanging upside-down under his horse and talking to Robin, look at the legs of the "horse": one of them has the visible joint of the knee (obvious as the light hits it when it bends) and the other doesn't look like it's actually touching the ground at all, though from the angle it looks as though the leg was intended to be seen as weight-bearing.
Continuity mistake: In the scene with the Sheriff of Rottingham and Don Giovanni discussing how to get rid of Robin, just after Don throws something at the guy on his left, the Sheriff leans forward with his arms on the table, then in the very next shot he is sitting back in his chair with his arms nowhere near the table - this happens a couple of times in this scene.
Continuity mistake: When the 'really white boy' is running from the Sheriff of Rottingham he comes through some trees in which rays of the sun are visible. As the sheriff and his men ride through there are more rays. When they leave there are no rays. In the next shot when the boy is talking to Robin the rays are back. Obviously this scene was shot in different order and throughout the day.
Revealing mistake: During the banquet scene, Robin slams the heavy carcass of a wild pig onto the table in front of Prince John. But throughout the fight, when the Sheriff and John are hiding, the carcass of the pig is being moved with the slightest movement as if it's hollow. A real wild pig of that size would not be moved so easily.