55 local extras were cast as "Roman Legionaries" and sent to a two-week boot camp, living in tents, to train as Roman soldiers. "Boot Camp" included military discipline (up at 5am bed by 9pm), marching, swordsmanship, camp building and dismantling, group training and maneuvers (day and night time training), and bathing restricted to the local lake without soap at night. 43 of the 55 completed "Boot Camp".
The names of the main characters, Lucius Vorenus and Titus Pullo, are actual historical. They are mentioned in Caesars' The Gallic war as two close partners with quarrels between them about each others bravery and who is to be promoted primus pilus. They are mentioned explicitly courageous when Marcus Tullius Cicero's brother was besieged. The audacity of Pullo is also noted, being similar to the Pullo in the series (Book 5.44).
Smuggling Princess Cleopatra into Alexandria tied up in a sack was described by the Greek historian Plutarch. The entire sequence was recreated in Rome, clear down to Cleopatra's demure pose before Caesar.
On 9 August 2007 a fire broke out at Rome's Cinecitta Studios back-lot. It destroyed 3,000 square meters of the 400,000 square meter "Rome" set but did not spread to the rest of the historic Studios. During the three hours it burned, a few of the highly flammable fiberglass sets in the "suburra" red-light district were destroyed but fortunately, the Forum, temples, thermal baths and other buildings were untouched. It is considered to be the largest open-air set ever constructed to date.
A man with Titus Pullo's background, i.e. son of a slave and therefore he must have been born a slave or at very least a freedman, could not have been a legionary. By Roman law, a legionary had to be born free. However, since his mother died when he was young it is entirely possible that he side-stepped this legal hurdle, and managed to join the Roman army by representing himself as an orphan.
According to James Purefoy, some of the props and drapes from the film Cleopatra (1963) found their way into the Alexandria scenes. This is not an especially far-fetched claim, as both projects were shot at the same studio.
The series' armor, helmets, and other metal costume elements were handcrafted by metal designer Luca Giampaoli. He handmade all metal costume elements for the principal actors, although "mass-produced" items (such a legionary armor) was replicated by metalwork companies in India.
The actors' regional British accents were used with effect to enhance the portrayal of the social distinctions of ancient Roman society; however after initial previews, some of the stronger accents were re-dubbed and toned down for American audiences.