Plot hole: When the three Marx Brothers are causing mayhem at the performance of "Il Trovatore," although we see scenes from several different acts of the opera, there seems to have been no intermission (or all the trouble would have gotten sorted out then, instead of at the end). You have to be at least a little familiar with "Il Trovatore" to notice this.
A Night at the Opera (1935)
1 plot hole - chronological order
Directed by: Sam Wood, Edmund Goulding
Starring: Chico Marx, Groucho Marx, Harpo Marx, Kitty Carlisle
Continuity mistake: In the scene where Harpo is climbing out of the brig and goes to the open window of the famous aviators, he is shown climbing in the room from the outside with the rope he's climbing on draped across his chest. When he gets into the room the rope has disappeared!
Otis B. Driftwood: Signor Lassparri comes from a very famous family. His mother was a well-known bass singer. His father was the first man to stuff spaghetti with bicarbonate of soda, thus causing and curing indigestion at the same time.