A lot of the location filming was done in Hungary because 1990s Budapest looked like 1950s Paris where the stories were set. Many of the minor acting roles, especially non-speaking ones, were played by Hungarian actors. Likewise some Hungarian crew members were used.
Sir Michael Gambon takes over the role of Jules Maigret after Richard Harris played the role in the previous English-language adaptation: Maigret (1988). Gambon and Harris shared another role, that of Albus Percival Wulfric Brian Dumbledore in the Harry Potter film franchise.
The script for episode 1 originally called for Maigret to check into his station in the morning and be told nonchalantly by the desk sergeant that nothing had happened overnight except "some prostitute's been beaten up". Michael Gambon felt that however in period this was, 50% of the audience would hate Maigret and his colleagues from the outset.