The movie is based on the books "Asterix the Legionary" and "Asterix the Gladiator". Apart from that, many minor characters in the movie are from other Asterix stories. For instance, the over-ambitious legionary is from "Asterix on Corsica", while the tradesman who sells Panacea and Tragicomix in Rome has the same appearance as a recurring Phoenician salesman.
The fat centurion whose camp the Gauls attack is a caricature of Pierre Tchernia, the writer of the movie. The same caricature of him appears in several Asterix books as he was a good friend of René Goscinny and Albert Uderzo, the Asterix creators.
In the movie Getafix tells that Panacea is the niece of the chief. This fact was not stated in any of the Asterix books.
Gordon Heath who provides the English voice of Julius Caesar for the film and again in Asterix in Britain (1986) was musical and life partners with Lee Payant, who provided the English voice of Asterix for the first 2 films.
English dub was recorded in France.