In the miniseries, Julia's son Gaius dies of a mysterious illness before she is banished, and Lucius dies after being wounded in battle. Historically, Lucius died of a mysterious illness before Gaius died on campaign, and both died after Julia was banished.
Marcus Agrippa is shown as being much older than Augustus. Historically, they were the same age.
In the miniseries, Tiberius is married to Vipsania at the same time that Julia is married to Marcellus. Historically, Tiberius married Vipsania in 19 BCE, when Marcellus had been dead for four years, and Julia had been married to her second husband, Marcus Agrippa, for two years, and was pregnant with their second child.
Augustus remarried a few months after Julia was born. Julia mentions that Livia had been married to her father for 20 years. Historically, Julia was 14 when she said that.
When Augustus throws Postumus against a wall, it wobbles.
In the Senate chamber, the famous statue of Romulus and Remus being suckled by a she-wolf is above the door. But the two children were added to the statue in the 15th century.
Herod frequently calls Claudius "little marmoset". Marmosets are native to the New World, which Europeans had not discovered in Roman times.
In the early episodes, several doors in the various buildings have modern doorknobs and other closure hardware, or the cutouts for them.
Augustus banishes his daughter Julia in 2 AD. Historically, she was banished in 2 BC.
Augustus thanks the poet Horace for his performance. Roman soldiers enter to inform Augustus of the troops slaughtered his at Teutoburg Forest. Horace died in 8 BCE, the Battle of Teutoburg Forest occurred in 9 CE.