Other mistake: Pintel and Ragetti fire the chain link cannonball, and it hits the square rigged mast aboard Interceptor. There's a shot of two men falling from the top of the mast, just before Interceptor's mast crashes onto the Pearl. They are not part of Jack's crew, who are all accounted for aboard the Pearl later. The only one of Jack's crew to die is the Asian man, when he's stabbed by a pirate and falls overboard. Nor can they be Barbossa's crew, because they haven't boarded yet. (01:27:00)
Other mistake: Keira Knightley has very obvious makeup applied to her cheeks and especially her eyes and lips throughout the movie. First example, when she gives Will the medallion in the cabin, and second, when Barbossa points the gun at her, before Jack shoots him. Actresses wear makeup in movies, but the lip color and eye make-up are unrealistic for a kidnapped Elizabeth. It shouldn't be as dark and apparent, as it is in this movie. (01:18:10 - 02:00:55)
Other mistake: When Elizabeth invokes the rite of parley with Captain Barbossa and first boards the Black Pearl, you can see the red flashing along with the booms of the cannons. As Elizabeth bargains with the captain, the flashes continue. After Captain Barbossa orders the guns stilled, the sound stops, but the flashes continue through the end of the scene even though they are no longer firing the cannons.
Other mistake: When Elizabeth is watching the attack on Port Royal from her balcony, the Black Pearl is at least two miles away. And yet one shot is able to hit the house.
Other mistake: When Captain Jack Sparrow is swimming up to the surface after ripping the dress off Elizabeth, he is swimming with both of his arms because he has Elizabeth draped over his shoulder. There is a considerable distance between Jack and Elizabeth. Also, when both of them are close to the surface, not only are both of Jack's arms out swimming, it can be seen that Elizabeth's double also paddles with one arm to assist in swimming to the surface. (Slow motion makes this easier to spot, but isn't vital.)
Other mistake: When Elizabeth stabs Barbossa, he pulls the knife out and there is blood on it. Why is there no blood on the sword later when he pulls it out of his stomach during his duel with Jack?
Other mistake: Ragetti's wooden eye always moves in sync with his real one. At that time, a prosthetic eye (wooden or otherwise) would remain stationary or move around independently from the real one. Even if this is a magical benefit of his 'cursed' state, it still moves in sync when he's transformed back into mortal form. (00:30:45)
Other mistake: When we see Jacoby lying face down with the axe in his back, we can see how far the axe sticks out. It's not deep enough in his back to stick out with that weight of wood and metal. That axe would never stand upright, it would fall to the side.
Other mistake: Translate problem - only in Hungarian version. In the scene, when Jack and Will are fighting, the blacksmith hit Jack from behind. Captain Norrington arrives, and say: Szép munka, Mr. Swan. (Good work, Mr. Swan.) The blacksmith's name is Brown.
Other mistake: When the Interceptor reaches the "boat graveyard" just off the dreaded island, it hits a pole or other assembly from another boat underneath them. It then "falls", literally plummets, downward and hits the ground with a thud. But wood doesn't "fall" downward through water, in fact, most wood swims. Even with other metal or other objects attached to it, this whole piece/assembly would have to be solid lead to "plummet" at that speed through water. No matter what the material is, it cannot go down that fast through water.
Other mistake: When Jack looks at the Pearl from his prison window, he is at least 10 boat heights above the ship. As we see throughout the movie when we look at the cannons of the Pearl and how they stand on the floor and shoot through the openings of the ship, there is no way that they could be rotated upwards to shoot as high as would be necessary to hit the prison cell.
Answer: The curse needs the blood of everybody who took a coin from the chest. All the other pirates have already contributed so, as the movie opens, the only blood needed is Will's, substituting for his father. During the finale of the movie, Jack takes a coin from the chest, adding himself to the curse, so his blood is now required as well as Will's.
Tailkinker ★
But I didn't see any blood on the coins, and none of the pirates cut themselves, even before Will became part of the mix.
Yes, the other pirates did cut themselves before Will came into it, off-screen. The lack of blood on the coins can simply be explained as most of it dripping to the bottom of the chest, it being washed away by storms blown into the cave, or by the fact that they didn't drop that much blood on it in the first place.
When they had Elizabeth they believed she was Bill Turner's daughter, but they all thought the curse had failed, none of them had cut themselves so it makes zero sense.
They had been collecting back the coins for years. During that time they repaid their own blood. All they needed was the last coin and the blood of Bill Turner to break the spell.
lionhead