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.
Mexicans Love Speedy Gonzales: Because of both this play, and Treasure Island's use of the Cornish accent as the pirate accent, the Cornish as a whole happily and willingly engage in antics that turn them into pirates. This carries to such an extent that there is even A Rugby team called the Cornish Pirates.
Values Dissonance: Frederick's "slave of duty" mindset will tend to strike modern audiences as merely silly. Englishmen of Gilbert's day, though, would have recognized it as a parody of their own code of conduct.