As Sir Percy awaits the firing squad, he asks Chauvelin if he knows poetry. He then recites several lines from Richard II. In Sherlock Holmes and the Secret Weapon, Holmes recites the same lines at the end of the movie.
Bunny Wigglesworth, with his "Sink me!" and scarlet suit, is somewhat obviously a(n unflattering) parody of Sir Percy Blakeney and the Scarlet Pimpernel