The main characters, Lucius Vorenus and Titus Pullo, are named after real-life historical figures. 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 as explicitly courageous when Marcus Tullius Cicero's brother was besieged. The audacity of Pullo is also noted, similar to the Pullo in the series (Book 5.44).
Fifty-five local extras were cast as "Roman Legionaries" and sent to a two-week boot camp, living in tents, to train as Roman soldiers. Training included military discipline (waking at 5 a.m., bed by 9 p.m.), 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. Forty-three of the 55 extras completed the boot camp.
On August 9, 2007, a fire broke out at Cinecittà's 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. A few highly flammable fiberglass sets in the red-light district were destroyed, but the Forum, temples, thermal baths, and other buildings were untouched.
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.
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.
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.
At its conception, the show had five seasons planned out before the first season had even aired. However, seasons 3-5 never came to fruition because the show was canceled during season 2, due to the enormous production costs. Much of the story material for seasons 3 and 4 was used in the final episodes of the second season to wrap up the show. There were talks of a 'Rome'-themed movie to give some of the storylines a proper closure, but this never materialized.
Narbo, the city that is often mentioned by Titus Pullo (Ray Stevenson) as the place where he spent his time off from the army and frequented prostitutes, was a real port city in Gaul (present day France). It was founded by the Romans and later developed as a stronghold for Julius Caesar by many veterans of his 10th Legion.
Due to the decision to broadcast the show at 9 PM on public television in Italy (as opposed to airing it around or after midnight, like other HBO series), several cuts and/or edits were required for the Italian version. Specifically, the profanity was partially removed in the dubbing, the violence was generally toned down and all instances of incest, rape and homosexuality were removed completely, while scenes of full frontal male nudity were replaced with specially shot alternate takes where the actors wore loincloths or towels. Despite all these changes, the show was still criticized by parents for being inappropriate in the 9 PM time slot, and a disclaimer was added stating that the series was intended for adults only.
Before the series was broadcast on British television, the BBC decided to edit the first three episodes into two for the British market. The network claimed that much of the exposition was deemed unnecessary since most British viewers are more familiar with Roman history than American audiences. Director Michael Apted, who learned about this by accident, stated that the network had probably done that in order to put more focus on the violence and sex, at the expense of the story. Following the controversy, the uncut first season was later aired along with the second season.
Alasdair Milne, who was the BBC's Managing Director of Television in the 1970s and Director-General in the 1980s, described the series as "rubbish, historically inaccurate and done simply to titillate American taste".