(at around 2h) The scene when Jack Sparrow calls Davy Jones "fish face", and sings to them "I got a jar of dirt", was unscripted and improvised by Johnny Depp, most of the reactions of the rest of the characters are real.
Johnny Depp's frequent collaborator, Tim Burton, contributed some of the conceptual designs of several crew members aboard the Flying Dutchman.
Gore Verbinski originally wanted Davy Jones to be Dutch, as he is the Captain of the "Dutchman". Bill Nighy, however responded, "I don't do Dutch. So I decided on Scottish."
Gore Verbinski initially rejected casting director Denise Chamian's suggestion to cast Naomie Harris as Tia Dalma, saying that she was too young for the role. Chamian insisted he give her a screen test. Finally, Harris's mother came with her for the audition, also serving as her dialect coach, since Dalma speaks in a partial Jamaican accent.
The dice game that Will Turner plays with Davy Jones is called Liar's Dice, a gambling game where each player has to make consecutively higher bids based upon how many of each die they claim are on the table (two threes, four fives, etc.), until a player is called a liar, in which case, all the dice are shown, and it's seen if the bid is correct. Normally, a player only loses a die when caught in a lie, and is not out of the game until he has lost all of his dice.