Major General Sir William Ponsonby's horse changes color in-between cuts several times before his death.
At the opening of the campaign (just after Napoleon's "God's got nothing to do with it" comment), French troops are seen marching down the road and across the fields. Troops did not march-in-step whilst on the move across country. It was too tiring and inefficient. Route step (aka route march) was used instead, in which the troops remained in a loose formation, but did not match their steps.
Some of the cavalrymen in the British cavalry charge can be seen to be carrying curved sabres, as dragoons they are heavy cavalry and should be carrying the straight bladed sabre. Sabres with curved blades were carried by light cavalry.
The Duke of Wellington says to Lord Hay "You're a lucky fellow Hay. To see such splendor in your 1st Battle. This was not Hay's 1st battle, he fought at Quatre Bras 2 days earlier ... and was killed there.
The Imperial Guard attack on the British line is shown as being broken by fire from the British guards. In fact the 52nd Foot, commanded by Lt. Col. Colborne, moved out of the British line and wheeled to the left to face the left flank of the Guard. They fired into the Guard and followed it up with a bayonet charge which, with fire from the 2nd Guards, caused the attack to fail, and the Middle Guard broke and ran.
Marshal Soult is shown during the scene of the Marshals revolting in April 1814. However, Soult was in southern France fighting Wellington at Toulouse at the time of Napoleon's abdication, and could not be at Foutainbleau.
In the party scene just before the battle, "Arthur. What an Englishman you are". Wellington was Irish and born in Dublin.
It is commonly, but erroneously believed, that Wellington belittled his Irish identity with the phrase "Being born in a stable does not make a man a horse". In fact this was said about Wellington but by the Irish catholic leader Daniel O'Connell at a political rally in Mullaghmast, Kildare in October 1843. Reporters recorded the comment at the time and it was cited in evidence in O'Connell's trial for sedition the following year.
Most cannons don't recoil at all. The few that do, only do so after a substantial delay, pulled back by crew off screen.
The French soldiers when marching are stretching their foot as it moves forward and are swinging their arms with a little up-turned movement of the hand. This is how Russian soldiers march, not French.
Despite all the pre-battle talk of mud, the ground at Waterloo is very dry, except for small areas that were clearly prepared for the cameras.
When the Prussians are first seen advancing through the wheat field, the wheat in front of them is trampled down (presumably from previous takes of the shot or the route they took to get onto the other side of the hill)
When the Allied cavalry are being run down by Napoleon's lancers and the cry goes out "Back, get back! Sound the recall!", one of the cavalrymen's trousers split and blue underwear can be seen.
During the scene where Napoleon and his staff see the advancing Prussians in the distance, where they raise their telescopes to their eyes, one officer on the right of the scene doesn't have a telescope and just pretends to raise one to his eye.
Soldiers can be seen fighting with packs on. Packs are an encumbrance in battle, and are typically taken off beforehand.
When the British Army form squares the top left and right squares from the aerial shot shows gun smoke on the bottom sides. As the French haven't reached them yet, they are only shooting at other squares.
When Gerard implores Grouchy to split their force and let him march his men toward the battle ("to the sound of the guns"), Grouchy replies "And divide my force? France would hang me." However, actor Charles Millot mispronounces "force" as "fourth".
When the Prussian troops appear, the music of "Deutschland ueber alles" can be heard. "Deutschland ueber alles" only became the national anthem of Germany in 1922. It was never used by Prussia.
The Duchess of Richmond tells Wellington to keep Hay safe as she doesn't want Sarah to wear black before she's worn white - in other words, to have to mourn Hay's death before they're even married. However, white did not become routinely worn at weddings in the West until after 1840, when Queen Victoria's unconventional choice of that colour for her wedding dress made it fashionable.
At about 1 hour 10mins, British troops are singing "Boney was a warrior" but this song was only written after Waterloo. Its lyrics comprise a short biography of Napoleon running up to his exile St Helena.
Many of the explosions and indeed the smoke columns are obviously generated by oil and its derivatives - 60 years ahead of its time. The explosive used in the battle was gunpowder only.
On the morning of the battle the camera pans over the troops before to focus on a soldier who is shaving in front of a mirror glass. In the background stands another soldier who clearly smokes a cigarette. Cigarette was not invented in 1815 and would it have been should have been so expensive that a soldier was unlikely to afford them. More usual was the pipe.
As the camera pulls back and then upwards towards the right, in the first establishing shot of the British army after the sun has risen on June 18 (the day of the battle, with Hougoumont in the background), the shadow of the camera crew can be briefly seen on the cannon that it pans over.
Mountains can be seen in the background during the battle. There are no mountains in this part of Belgium.
When the French cavalry were attacking the British squares, explosions were seen and heard all the time in between the squares. It is unclear if they were from French or British guns but the inaccuracy of the time would mean neither side would fire at such a melee for fear of hitting their own side.