Too many Ponsonbys
A somewhat confusing episode in the movie comes when Maj. Gen. Sir William Ponsonby and Uxbridge are taking snuff, and Ponsonby describes how his father was killed when his horse became mired down and he was surrounded by lancers. In fact, his father was a politican, not a soldier, and the story he's telling is a description of his own fate. Why the moviemakers decided to present it this way I do not know.
In the movie, William Ponsonby hands something, perhaps a medallion, to another officer with the instructions "give that to my son" just before his horse becomes bogged down and he's surrounded by lancers who quickly do him in. In reality, the other officer was his second cousin, Sir Frederick Cavendish Ponsonby, and the depiction of him immediately thereafter being stabbed in the back by a lance is in fact accurate. However, even though he had already sustained two or three serious wounds, the lancer didn't kill him.
As he lay helpless on the ground, bleeding from several wounds, he was robbed by a French skirmisher. Then he was discovered by a French officer who provided some assistance (while inaccurately reporting that Wellington had been killed). He was followed by another French skirmisher who fired over Frederick's prone body and kept up a running commentary on the progress of the fighting. He then departed, at least doing no further harm. Next came some Prussian cavalry who stampeded over Ponsonby, and after that a Prussian who tried to rob him, even though he had nothing left to steal, and they were supposed to be allies.
Finally, a British foot soldier came on the scene, and agreed to stand guard for the rest of the night. In the morning, the soldier spotted some British troops nearby, and a cart was sent to take Ponsonby to the nearest hospital. Unlike the French, the British had no proper ambulances, and the trip in the cart was agonizing. However, against all odds, Frederick Ponsonby lived. During his recovery he was nursed by his sister, who had an affair with Lord Byron. He later married and had several children.
I did NOT make this story up... I don't think I could have. Biographies of both Ponsonbys are to be found on Wikipedia, along with a link to an article about the sister who had the affair with Byron.
I also have to wonder about the wisdom of sending cavalry armed only with sabers (total "reach" of about 5 feet) to tangle with cavalry carrying lances 10 feet long. Yes, I know the cavalrymen usually carried pistols as well, but it's difficult to fire a gun from horseback at all, let alone hit the guy who is about to spear you.