An Alexander Korda version was abandoned back in 1937. Directed by Josef von Sternberg, it starred Charles Laughton in the title role alongside Merle Oberon. A car crash involving Oberon was the main reason cited for the cancellation, but sources say it was a troublesome shoot, with Laughton the main source of the problem.
The series was filmed over a period of six months in a BBC studio. Charlton Heston was considered for the title role, but the idea was abandoned because of the extent of the shoot, and Heston's U.S. residency.
Claudius was 53 years younger than his great-uncle Augustus. In real life, Derek Jacobi is a year younger than Brian Blessed. Similarly, Caligula was 22 years younger than his uncle, and successor, Claudius. Sir John Hurt was 14 months younger than Jacobi.
George Baker, who was in his early 40s, started a diet and exercise routine to play a young Tiberius. He managed to reach is 24-year-old weight. His exhaustion from exercising so much and eating so little made it easier for him to play a bitter, often frustrated character prone to mood swings.
When Derek Jacobi was first offered the role of Claudius, he mistakenly believed he was being considered for the character of the same name from "Hamlet", and opined that he was too young. He eventually played King Claudius of Denmark in Hamlet (1996).
Brian Blessed originally auditioned for the role of Tiberius, but was eventually persuaded to play Augustus instead. He recounted Herbert Wise's saying "be as you are, full of flannel", and that he should always play Augustus as an ordinary person, because the reactions of those around him would make him the Emperor.
Sir John Hurt revealed that he declined the role of Caligula when it was first offered to him. Because of the time-span of the production, the fact that Derek Jacobi was the only cast member to appear in every episode, and the subsequent commitments of the other cast members, Herbert Wise decided to throw a special pre-production party so the entire cast and crew could meet. Wise invited Hurt to the party hoping he would reconsider. When Hurt met the cast and crew, he was so impressed that he immediately took the part.
Many assume the poor audio quality on the DVDs is because of faulty remastering. During filming, microphone placement on set was not as polished as it could have been, or as it might be now, and it shows up more clearly on the DVD because of higher fidelity. At certain moments, an actor or actress may be in the rear of the set, and their voice is not picked up clearly. The actor's voice gets louder as they advance.
Peter O'Toole, Siân Phillips' husband at the time, reassured the cast at an early showing that the audience would love it, even if the critics didn't. She recalled that he found the reviews of the original books that were similar to the first reviews on the television series.