Napoleon did, after all, invade Egypt, and fought a significant battle within sight of the pyramids in 1798. He appears to have visited the pyramids in person, though no accounts of him shooting them with a cannon have been found. Also, it’s logical to believe that someone would have noticed that the top of one of the pyramids had been blown off over the last 225 years.
According to historical author Shannon Selin’s amusing demystification of Napoleon’s time in Egypt, Scott and Scarpa are mixing the genuine Battle of the Pyramids with a myth that Napoleon’s forces shot off the Sphinx’s snout during target practise. According to Selin’s research, what happened when Napoleon visited this global wonder was less disruptive and even endearingly nerdy. Bonaparte challenged some of his entourage to climb a pyramid; the winner was a mathematician named Gaspard Monge, who took a taste of brandy with his competitors as they reached the top. Then Napoleon calculated that the pyramid stones could be used to construct a 10-foot wall around all of France, a calculation that Monge allegedly verified.
It would have been good to see that on screen as well. But Scott recognises a grandiose visual metaphor when he sees one, and with these images portraying Napoleon progressing from vaporising revolutionaries to assaulting the embodiment of history itself, he’s clearly making his point.