Banned in China: Benito Mussolini was under the impression that the entire film was a satire on Fascist Italy and had it banned there as a result. Humorously enough, the most common criticism leveled against the movie in America was that it didn't criticize fascism strongly enough (the Marx Brothers themselves were reportedly ecstatic to know it got under the skin of an actual fascist dictator).
Beam Me Up, Scotty!: Rufus T. Firefly is often quoted as saying "A child of five could understand this. Send somebody to fetch a child of five". However, the actual line is "Why, a four-year-old child could understand this report! Run out and find me a four-year-old child, I can't make head or tail of it!"
Cut Song: Screenwriters and songwriters Bert Kalmar and Harry Ruby wrote the song "Keep on Doin' What You're Doin'" for Zeppo Marx and Raquel Torres to sing. When that romantic subplot was cut, Kalmar & Ruby recycled the song for Hips, Hips, Hooray! with Bert Wheeler and Robert Woolsey, who sang it with Dorothy Lee and Thelma Todd.
Executive Meddling: Contrary to popular belief, the film was not an Acclaimed Flop which convinced Paramount to drop The Marx Brothers. In fact, it was the opposite: the Brothers voluntarily broke off their four-picture deal with the studio while this one was being written when they learned that Paramount wasn't giving them their cut of the profits from the last three pictures they'd done togethers. Paramount tried to move ahead with the picture with a different cast while the Brothers began work on a production of Of Thee I Sing. When funding for the play fell through, they returned to Paramount and agreed on a one-picture deal to finish this film.
Fake Nationality: By default. Every character but one is either stated or implied to be a citizen of either Freedonia or Sylvania, neither of which actually exists. The only exception is a dignitary from the equally-fictional Mufhtan.
An early draft of the script introduces Freedonia's new dictator Rufus T. Firefly as an agent for an ammunition company, which led to lots of ammunition-salesman jokes and intertwined with the movie's war theme.
In the original script, Chicolini and Pinky were cousins and Bob was Firefly's son. Also, Pinky was originally called Skippy.
Early drafts of the script included scenes in an opera house and aboard a zeppelin.
Vera was Trentino's niece in early drafts.
In the original script, there was to be a romance between Vera Marcal and Bob Roland but it was cut before the picture's release, much to Zeppo's annoyance.
Sylvania was called "Amnesia" in early drafts.
Zeppo, who was keen on getting out of the Marx Brothers act, saw their contractual violation to Paramount as an opportunity to break out on his own. Had the other three not convinced him to stay, they would have replaced him with their fifth brother, Gummo, making it his only film appearance.