Early in the film, count Louis de Breze claims that he and Diane de Poitier had no children. Their marriage was not childless, they had two daughters, born 1515 and 1518.
In the film, after pleading the king for mercy on behalf of her husband count Louis de Breze, Diane is watching the adult prince Henry outside the palace wrestling with his groom. In fact, it was her father, not the count who was charged with treason in 1523 when the prince was only 4 years old, born 1519.
Throughout the film, the French royal house of Bourbon is named by all the actors as "Berr-bon", as if it were the American whiskey drink. It should be pronounced as "Boor-bon", as in the biscuit.