These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: A Night at the Opera
Crowning Music of Awesome: Harpo's solo performance of "Alone". A lovely song, and perhaps Harpo's best performance in any of the movies.
The Marx Brothers picked exactly the right opera to send up. The plot of Il Trovatore makes very little sense anyway (partly due to the librettist chopping out more than half of the story in between acts), but the music can stand up to anything.
Designated Villain: Lasspari is at least unpleasant enough that the audience wants to see him eat humble pie, but Gottleib is never portrayed as anything but a decent man looking out for his opera and his investors. Sure, he doesn't like Driftwood, thinking him a cheat, a hustler, and a fortune hunter... but Driftwood is all of those things, and he has no particular grudge against Tomasso and Fiorello until they break into his business and start ruining his show and repeatedly injuring his head.