While the rebels are firing on the British fort, one of the rebels firing is shown needing help in getting his musket ready to fire. The man behind him reaches over the shooters shoulder to cock the gun and lower the "frizzen" (the strike plate that generates the spark in a flint lock weapon) so the shooter can fire.
The shooting demonstration done in court was described as taking place at twenty paces. Twenty paces is equal to approximately 60 feet; the shots fired in the film were at approximately 20 feet.