The tricolour is flown with a blue fly.
Ducos says that Calvert's camp is 50 miles away. France adopted the metric system in 1795 and before the Revolution used lieue (leagues) to measure distance. France never used the mile.
At about an hour in when the french surgeon is preparing to remove the musket ball from the British officer's leg, he is holding the forceps upside-down, curved away from the wound. they should be held curved down to be able to enter the wound and so remove the ball.
After the battle, one of the "dead" French can be seen looking at the camera and opening and closing his eyes.
At the initial failed storming of the castle, the British troops are using extension ladders, which would not be invented for another 50 years.