When the confederates are running the cattle across the bridge there are fences protruding out to the sides to guide them across. The fences were not there when they went to steal the cattle.
Sergeant Hatcher is wearing a bandoleer of .45-70 cartridges at least eight years before the .45-70 was developed.
Despite the firepower of the Union Cavalry at the bridge, not one steer is seen to fall down dead or wounded. There are fallen cattle seen after the herd has crossed the bridge, but these are obviously live cattle with their legs tied, as can be seen when they struggle to stand up.
In the ambush at the bridge, the Union solider nearest the camera has a '66 Winchester with a wooden forestock, not a Henry as would be normal for the period.
The Union troops and cannon are set up on the near side of the bridge where they get overrun by the cattle. They would have been safer on the far side of the bridge and the distance over the river would not have been a factor for the cannons to be effective. The Rebels would not have been so easily able to cross the bridge if the Union troops were deployed on the other side to stop or impede them until the main Union force overtook them.