Other mistake: At the beginning of the movie in the castle two servants pull out a large chair for Robin to sit down. After the spear is thrown at the chair Robin picks it up over his head and throws it a good 15 feet. Quite a feat for something that was made out of solid oak.
Other mistake: When King John's henchman goes to slap Robin across the face the camera suddenly cuts to Robin kicking the henchmen in the chest, sending the henchman backwards into the crowd. Indicating an obvious retake that Flynn had lost his footing during the 1st take. After the henchman barrels backward it suddenly cuts to John speaking with Gisbourne about revenge.