The scene when Jack Sparrow call the Flying Dutchman "fishmates" and sing to them "I got a jar of dirt" was actually unscripted and it was improved by Johnny Depp, mostly of the reactions of the rest of the character are real.
The scene where Sparrow is hurled across a canyon and landing on his feet while tied to a pole, is amazingly not using CG nor any other sort of camera trickery, not even wires. A man was actually tied hands and feet to a pole and then, by the use of specially created rigs (along with a dose of scientific pre-calculations for acceleration, distance etc), physically catapulted over that junction, doing a somersault mid-ways in the air and landing perfect on his two feet - all in one take! (Source: The "World Stunt Awards" TV show, 2007)
Actually, all of Davy Jones's crew were actors. They all wore dark gray motion-capture suits and before they could be filmed they had to be scanned in order for the computer to place the crew images over the top. Bill Nighy wore makeup around his eyes and mouth in case computer rendering failed to look realistic during extreme close ups (fortunately this was never needed).
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 partial Jamaican accent.
Rolling Stone Keith Richards was set to make a cameo appearance as the father of Captain Jack Sparrow, but Richards had to pull out of the project due to his commitment with The Rolling Stones world tour. Johnny Depp had previously said that his performance as Jack Sparrow was based on Richards.
When Mr. Gibbs is enlisting new recruits at the tavern, a bunch of men are pulling a man out of a well, and he slowly spits out water. This is a recreation of a scene in the Pirates of the Caribbean ride at the Walt Disney theme parks.
For the film's release, the Walt Disney Company redesigned the Pirates of the Caribbean rides in Walt Disney World and Disneyland to feature captain Jack Sparrow, Barbossa, and an appearance by the film's supernatural character Davy Jones as part of the attraction and premiered on the same day as the film.
In an interview with CGSociety, Visual Effects Art Director Aaron McBride revealed that when he was given the task of doing photo-real illustrations of Davy Jones, there was talk that Christopher Walken would play the role.
Orlando Bloom and Bill Nighy have both appeared in adaptations of The Lord of the Rings. Bloom played Legolas in Peter Jackson's films, while Nighy was the voice of Sam Gamgee in the BBC Radio version.
Throughout the movie, many references are made to the original Pirates of the Caribbean: The Curse of the Black Pearl (2003). These include the following: Cutler Beckett is corrected by Elizabeth and Will when he fails to refer to Jack Sparrow as "Captain" (Jack insisted on being called "Captain Jack Sparrow" in the first movie); Governor Swann breaks off an arm of a candlestick inside the dungeon (the same happened to Will in the Governor's house in the first movie); Governor Swann asks where the "dog with the keys" is; the dog is still holding the keys in the rowboat; Jack asks, "Why is the rum always gone?" (he asked Elizabeth the same twice in the first movie); Will gets slapped by a lady in Tortuga (Jack's being slapped by ladies he once mistreated was a running joke in the first film); Jack says "Hide the rum" when Elizabeth arrives (Elizabeth burned his rum in the first movie); a running gag plays on the fact that Jack the monkey is immortal (he stole one of the Cortez coins in the post-credits scene at the end of the first film).
When the sailors fight over the dress on the ship on which Elizabeth has stowed away, they talk about the ghost of a woman who was widowed before her wedding. This is a plot point in the Disney Ride "The Haunted Mansion".
The two sailors quarreling over Jack's hat on the boat which is then sunk by the Kraken are from Cyprus. The sailor on the left is Turkish-Cypriot while the other on the right is Greek-Cypriot and speaks the Greek-Cypriot dialect.
It is stated in the DVD commentary that the scene where several people argue how to pronounce "kraken" was added due to an error by Kevin McNally. The word is said "Kray-ken", but when McNally first said the creature's name, he called it the "Kracken", and this caught on with the rest of the cast. The scene was added to show how the creature's name is actually said.
The shack by the river as the crew go to see Tia Dalma is identical to the shack on the far side of the river across from the boarding dock of the Magic Kingdom's "Jungle Cruise" ride in Orlando, Florida.
This marks famed special-effects house Industrial Light & Magic's first Oscar win since Forrest Gump (1994) 12 years previously. This is also the only "Pirates of the Caribbean" film to win the award in any of its nominated categories (as of 2010).
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 his dice.
The trivia items below may give away important plot points.
For a dose of authenticity in the final twist at the end of the film, the actors were not told, prior to filming, that Geoffrey Rush would be appearing in the movie. They were told, before the scene was shot, that the person coming down the stairs would be Anamaria (Zoe Saldana) from Pirates of the Caribbean: The Curse of the Black Pearl (2003); the looks of surprise on their faces as Rush descends are genuine.
When Jack offers the monkey to Tia Dalma, she opens the cage, setting the monkey free. The monkey then runs off and starts playing with a pair of boots that are attached to a leg (presumably Captain Barbossa's).
When Jack Sparrow is at Tia Dalma's hut, there is a necklace on the table when Jack is stealing the ring. The picture on the necklace is the same image on the music box on Davy Jones' pipe organ, a hint to a major plot point in Pirates of the Caribbean: At World's End (2007).