Revealing mistake: After the prince is crowned king, Robin and his mates leave the castle. If you look to the upper-right of the screen, atop a hill in the distance, you can see a modern-day metal telegraph tower (cinematic version).
Revealing mistake: Early in the movie, as they are heading down to the beach in France to board the ship to England, a plane contrail is seen in the sky.
Answer: By "Wind-up lute", I assume you mean the hurdy-gurdy. Certainly, instruments fitting the description of the hurdy-gurdy were around in the time when Robin Hood was set.
Madstunts