Since Pirates of the Caribbean was originally conceived (and still very much is --Ed) as a sequel to Sea Dogs, it's idea of the Caribbean is the same as it's predecessor. The game takes place over a set of fictionalized islands, towns and forts that you won't find on any real-world maps of the region.
Learning rumors and information in taverns is sometimes a good idea. However when in a tavern, one of the game's voice samples bravely boasts "I made the Kessel run in under 12 hours". This is a reference to one of Star Wars: A New Hope's most famous lines in which Han Solo boasts that he made the Kessel run in under 12 parsecs. It's also one of the film's most famous goofs since a parsec is a measurement of distance, not time.
The game was called Sea Dogs 2 up till just a couple months prior to release. Then they changed the name to Pirates to the Caribbean to profit from the popularity of the Disney movie.
However, the game hasn't changed a bit because of this and the game actually has nothing to do with the story or characters from the film, with the exception to the voice over which is one of the actors from the film.