Continuity mistake: The movie starts with the shot of a sculpture and a raven landing on it. From the side shot the raven is on the left sculpture, from above he is on the right sculpture.
Continuity mistake: When the Professor is reciting a poem to the ladies from the church, there is a burning candelabra on the mantel behind him. In alternating shots, the candles have wax dripping down the sides and then they do not.
Plot hole: When Gawain is repairing the hole in the vault wall, a security camera is visible in the top corner in the room.