Factual error: When Lucrezia is lying in bed suffering from swamp fever, probably malaria, she blames a mosquito for the disease. But she could not have known this; the discovery of the transmission of malaria by mosquitoes was not made until the late 19th century. The prevailing theory of disease transmission at the time was via miasma, or bad air.
Factual error: Cardinal della Rovere says he wishes to join the Dominican Order instead of the Capuchin Order because the former's rule is stricter. In actual fact, the Capuchin rule is one of the strictest of all Roman Catholic orders, something which della Rovere would certainly have known.Necrothesp
Factual error: After the army's retreat, as Juan Borgia is walking through the great hall, he calls the priests fleeing with the books "rats deserting a sinking ship." But then says "you're like lemmings running to your doom." However, the notion of the suicidal lemming running to its doom came from Disney's 1958 film "White Wilderness", which was later proved to be a hoax. Lemmings do not commit mass suicide nor "run to their doom" so such an analogy would never have been said, or even understood. (00:42:55)Bishop73