I almost joined into a debate on this movie when some (I assume American) stated that Stonewall Jackson would not have been overrun like the Danes were in this battle. Some European (I assume) said that Stonewall's army would have been crushed by the Prussians because of their superior weapons, i.e. needle guns and artillery. But I refrained for now until I can support my memory that the Prussian field artillery was no larger than 6 pounders. and the U.S. 3-inch rifle was superior or equal to anything the Prussians had in 1864.
The full episode shows the Prussian siege artillery with a firepower that looks more like WWI than 1864. I do know enough about their Krupp guns yet.
Also this was a siege, and Jackson would not allow himself to be put into that situation in the first place.