Dark Waters (Once Upon a Time) is to take Snow's heart. The Land of Untold Stories is revealed to be the Mysterious Island from the book as the same name. The "Nautilus" is based on the submarine from "Twenty Thousand Leagues Under the Sea". Captain Nemo based on the protagonist from Jules Verne's novel "Twenty Thousand Leagues Under the Sea". Hook refers to the giant squid that attacks him as a kraken. The kraken is a legendary sea monster of giant size that is said to dwell off the coasts of Norway and Greenland. The episode posted its lowest numbers so far in the series, as
20,000 Leagues Under the Sea (1954 film) which Douglas had sung in the movie "Man Without a Star" (written by Lou Singer and Jimmy Kennedy), was the B-side. Both songs can be found on the 2008 digital release of the film's soundtrack. In the film, Johann Sebastian Bach's "Toccata and Fugue in D minor" is played by Nemo on the Nautilus's organ, but James Mason's playing is actually dubbed by an anonymous organist. On January 29, 2008, Walt Disney Records released a 26-track digital album containing the music of Paul Smith's original soundtrack score to "20,000 Leagues Under the Sea" plus both sides of the "A Whale