Actor Paolo Stoppa, who plays Pope Pio VII in this movie, has the unusual record of having played the role of a Pope no less than four times in his career, including Saint Peter in Nerone (1977), Alexander III in Becket (1964) and an unnamed Pope in Jus primae noctis (1972).
Actor Giorgio Gobbi, who played marquis' friend Ricciotto, stated in an interview that Alberto Sordi initially didn't want him for the role due to his young age. At the end, director Mario Monicelli decided to go ahead with him and Gobbi and Sordi got along very well together and had a lot of fun while filming.
The most famous gag in the movie is probably the one where the Marquis Del Grillo (Alberto Sordi) says: "Mi dispiace ma io so' io, e voi non siete un ca**o" ("Sorry, but I am myself, and you are nobodies"). This sentence is taken from the Roman sonet Li soprani der monno vecchio (1831) by Giuseppe Gioachino Belli, cited also in the movie Remo e Romolo - Storia di due figli di una lupa (1976).
The location of the theatre scene is in Amelia (Umbria), in the same theatre where the scene of the circus of Le avventure di Pinocchio (1972) was filmed.
The filming of the marquis' house wasn't made in Rome but in Lucca (Palazzo Pfanner).