And You Thought It Would Fail: Zero Mostel was very reluctant to do the show, and in fact the song "Comedy Tonight" was originally only added to appease him. And of course it ended up being one of his most famous roles (especially since unlike Fiddler on the Roof, he got to be in the movie).
Award Snub: The original production won the Tony Award for Best Musical and Best Book, but Stephen Sondheim's score wasn't even nominated. Granted, the score is considered one of Sondheim's weaker efforts (after all, it was his first Broadway show where he did both the music and lyrics), but it's still much more beloved and iconic than the year's nominated scores, with the exception of the category's winner.
Genius Bonus: Possibly unintentional, but an exchange added for the film (Lycus' scene with Crassus) is quite similar to one from Plautus' original play "Pseudolus," where the Lycus equivalent Balio hears someone is looking for a man with a quite unflattering description, and simply replies "It must be me."
Roy Kinnear has a cameo in the film as a gladiator trainer who's accidentally killed. Two decades later, he really was killed in an accident (falling off a horse) while filming another Richard Lester movie, Return of the Three Musketeers.
Buster Keaton's death before the film was released paints a dim picture of how long Erronius has to enjoy his newfound family (though considering how poorly Keaton's career went after the advent of the talkies, it at least meant he went out on a relatively high note).
In the final reprise of "Comedy Tonight," Senex instead says "A tragedy tonight," implying that he's going to kill his wife. Domina's film actress Patricia Jessel died just two years later at a young age.However this line could just be interpreted as how little he is looking forward to continuing wedded life with Domina.
In the movie anyway. Philia: "3 and 5, I always confuse the two."
"Comedy Tonight" promises "baritones and basses." There actually aren't any bass parts in the original show, but then Leon Greene was cast in the film, requiring both his songs to be lowered an octave.
Ho Yay: Pseudolus and Hysterium replicate Hero and Philia's Imagine Spot of running romantically through a forest and field together, and sing a reprise of "Lovely," which was originally the young (heterosexual) lovers' falling-in-love song. At first it's just Pseudolus trying to convince Hysterium to go along with the crossdressing thing, but then Hysterium starts really getting into it and the Ho Yay skyrockets from there.
The Roman Chief Guard is played by John Bluthal, who would later be best known for playing Frank Pickle in The Vicar of Dibley.
They Wasted a Perfectly Good Character: Or rather, actress, as the songs cut from the film mean that Patricia Jessel as Domina only gets to display her magnificent singing voice on three words with her rendition of "something for everyone" in the final song. And she passed away just two years later at age 47 without doing any other musicals, robbing us of hearing what she could do with a bigger singing part.
