The page in Mickey's book depicting mermaids is actually a concept drawing done by Disney artist Mary Blair during preproduction of the film 'Peter Pan.'
Goofy appears to be playing Captain Nemo's organ from '20,000 Leagues Under the Sea.' Incidentally, that same organ can now be seen in Disneyland's 'Haunted Mansion.'
Contains several references to the former Disneyland attraction "Submarine Voyage" and the film which inspired it '20,000 Leagues Under the Sea.'
The sub is called "the Duckilus," an obvious play on "the Nautilus," Captain Nemo's iconic vessel from '20,000 Leagues Under the Sea.'
Pinocchio and Mister Geppetto from Pinocchio (1940), Pinocchio cameoed in this episode, though the former speaks with a proper Italian accent in it instead of the American one he has in most of his appearances.