When Cesare enters Milan with the french army, he finds Leonardo da Vinci's bronze horse partly dismantled, because the Duke of Milan had it molted down for cannons. In reality, Leonardo's horse existed only as a full-size clay model, from which a bronze horse should be made. The casts and 70 tons of bronze were ready when in 1494 the bronze was needed as cannons to defend the city, so the final bronze horse was never molded. The clay model was still the one in Milan when the french invaded Milan in 1499.
Pope Alexander mentions that oratorios would be performed in the Year of Jubilation, but oratorios did not exist for another hundred years.
In speaking of the Sword of Longinus, the Jewish cleric says he could "'gift" it to Alexander. The use of "gift" as a verb is a very recent neologism. The English used at the time, and until a few years ago, would have been to "give" the sword.
(at around 17 mins) As the Jewish leadership is exiting the room, a production camera can be seen on the left side of the frame for a few moments before being covered again by a door.