Factual error: Caesar and Brutus grow up together in the book, being the same age. Caesar was actually born 15 years before Brutus and some historians believe he could have even been Brutus' father.

Plot hole: When the two boys grow older they set aside their first name and go by their second. Gaius was called Julius instead while Marcus was called Brutus. This is however inconsistent. Gaius full name was Gaius Julius Caesar and Marcus' was Marcus Junius Brutus. They should either have been called Caesar and Brutus or Julius and Junius, not Julius and Brutus.