Trophies/Achievements titled "It's Aliiive" and "Yes, Master", the later of which is awarded after Wilbur gets the Igor outfit. Also, Mayor Whale is named after director James Whale.
In Chapter 2 (Nate's section), after the parrot falls into the blanket-covered barrel, Nate remarks, "Goodnight Gracie". This is what George Burns would tell his wife Gracie Allen to say at the end of every episode.