As Andrew waits behind in the trench to shoot deserters, we see that he is surrounded by rats and dead soldiers, but when the camera angle changes as a couple of British troops descend the ladder, the rats and bodies have disappeared.
The horse is shown galloping in a trench and never having to turn, suggesting the trench is long and straight. In reality, trenches were built with zig-zags so if the enemy got in, it couldn't shoot down the trench and easily hit someone.
When Lt. Waverly and Captain Nicholls are discussing the new caps, Nicholls says "...I fancy that cap. I'll kill you first of all." The shot changes to show Waverly's reaction. Here, Nicholls's jaw can be seen moving as if he's speaking, but nothing is spoken.
Practice Cavalry charge scene: The adult horse Joey can be seen just prior to the practice cavalry charge with a white mark in its hair above its right eye. During the charge there is a close up of Joey's face and the white mark is absent. The color of this horse is also a slightly darker chestnut to that of the horse at the end of the charge. Subsequent shots through the film do not show this white mark and especially the shots of the young horse the mark is also absent.
Before leaving for France Major Stewart gives the order for battle; there is to be no polish so that a glinting bridle or stirrup would not give away their position. In the scenes set in France all the metal on the horse's bridles is freshly polished.
When Albert is trying to befriend Joey with an apple which he is holding out at arm's length, the apple is whole. There is a short cut as Joey looks back at his mother and when we see the apple again, it has a big bite taken out of it. But Albert has not moved.
When the younger Schroeder brother, Michael, is entering the lines to march to the front, he enters the left line (walking direction). His brother, Gunther is packing the horse and follows to get him out of line. At that moment Michael has switched line and walks in the right line of the column.
When the cavalry charge through the grass towards the Germans you can see they are running in trails previously made. When they burst into the open you can see how the grass has been flattened by a previous charge.
The young German deserter is named Michael. His named is pronounced the way an American/Englishman would pronounce it (with a k sound). A German would pronounce it with the a "ch" sound, which is an unvoiced soft aspirative sound not found in English. (Comparable to the Scottish sound "ch" i.e. in "Loch".)
After the horses pull the heavy gun to the top of the hill, the gun crew loading the gun only place the projectile in before firing - in reality, the shell would have to be followed by at least one powder charge to propel it. Large caliber artillery pieces and naval guns load the projectile/shell and the propellant separately; smaller ones have them assembled as a cartridge, similar to what a rifle, machine gun or handgun fires.
In the trenches scenes the British troops shoulder badges say Dorset but they refer to themselves as Devon boys during the assault on the machine gun nest. There were different regiments from each neighboring county until the Devon and Dorset regiments were merged until the 1957 defense review.
The German Army camp is on an open field in enemy territory without any sentries, with around a dozen machine guns forming a defensive line at least 100 yards away from the camp, with nobody guarding these machine guns and with the camp right in the middle of the firing line of the machine guns.
When the German machine gunners reach their guns, they open fire without elevating their guns thus spraying bullets at around 1 to 2 feet above ground. However dozens of horses manage to come through this hail of bullets unharmed, while their riders sitting at least 5 feet above the ground die in scores.
The goof items below may give away important plot points.
Before Captain Nicholls goes to his death in 1914, he listens to a gramophone recording of the beautiful song, "Roses of Picardy" by Frederick Edward Weatherly and Haydn Wood. Unfortunately for him, the song wasn't written until 1916.