Why do the slaves in Blackbeard's mine sing distinctly modern songs that seem out of place even in the Anachronism Stew? The answer lies in the magical island's name: Neverland. It's separated from Earth not only in space, but time as well, which is why Blackbeard's pirates represent such a mixture of times while James Hook seems to be an Old West prospector with knowledge of mining and explosives far ahead of Blackbeard's time. Blackbeard kidnaps slaves from all manner of times, but can't go too far into the future due to the advancements in technology making it unviable for his ship to be able to get in and out; see how they barely escape the WW2 fighter planes. So at some point in his explorations of getting slaves for his mines from different times, he kidnapped some people who knew the songs in question and liked them enough to make his entire workforce learn them for special events like the arrival of new slaves and the daily executions.
In the beginning, a voiceover states that the best of friends become the bitterest of enemies, and vice versa. Anyone familiar with the Peter Pan stories expects this to be Peter Pan and Captain Hook, especially since they start out as friends. Except they remain friends to the end of the movie. Barring a Face–Heel Turn in a sequel, the opening is actually describing Blackbeard and Mary, or, alternatively, Hook and Smee. As far as the enemies becoming friends, the best example in the movie is Hook and Tiger Lily.
