At about 40mins in when Jacob is teaching archery to the prince, uses the command, 'fire!'. That term came about from, 'give fire!' in musketry. the correct term for archers in the period and still now is, 'loose!'. About 2 minutes earlier, same mistaken word was used when the prince said "I want to fire arrows like you".
About 50 minutes in, Jacob unties his wrists by burning the rope, instead of using the sword he just got back from the guard.