Continuity mistake: Barbossa rips the chain and medallion off Elizabeth's neck, puts it into her palm, then cuts her hand. He takes her hand in his and he turns hers over so it's palm down. The chain can be seen in the close-up and wide shot, dangling down between her fingers and the chain is NOT clasped shut. In the next close-up of the chain and medallion falling into the chest, the chain IS clasped shut. (01:11:55)
Revealing mistake: In the scene where Jack and Will have just taken the Interceptor and the Dauntless is coming about, the men on the row boat get caught in its path. A second after the men abandon ship, you see the boat get destroyed. If you look closely at the forward wake of the ship, the boat is too far away to be destroyed by the front of the ship. And since the boat initially goes down when it's struck, it can't be the keel of the ship, since that would send it up. (00:48:05)
Visible crew/equipment: Aboard the Interceptor, as Jack asks, "Can you sail under the command of a pirate...?" at the upper right corner of the screen, the corner of the crew's white reflector screen is perfectly visible in front of the boom. (00:50:15)
Visible crew/equipment: During the battle between the Interceptor and the Black Pearl, as Jack takes Elizabeth aside and asks her where the medallion is, on the top right corner is a film crew member's hand with a watch on it. (01:29:05)
Revealing mistake: During the sword fight in the blacksmith's shop, Will pulls a blade out of the fire. While fighting Jack, the heated blade sparks when their two swords clash. When Will blocks a hit from Jack, the impact is far BELOW the red/orange hot section of Will's sword, yet it sparks right at that spot. It also makes a kind of sound like electricity crackling. A heated blade would not make this noise, nor would it send out embers or sparks where it is not heated. Only the tip is heated, however the whole blade has an electrical current running through it, mentioned in another mistake. (00:24:15)
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.
Continuity mistake: When Will and Jack are in the bar in Tortuga, Will stands with his back to the wall and on that wall is a shelf with a candle. The candle height changes and the candle drippings are very different in these shots too. Also, shots in the deleted scenes. (00:52:10)
Continuity mistake: When the medallion drops into the chest, and when Barbossa removes it, there is blood on both sides of the medallion. When Barbossa hits Elizabeth and she falls, the medallion falls near her. In this shot we do not see any blood on the medallion. Yet when Will rescues Elizabeth, she reaches for the medallion and it now has a very obvious blood stain on it. (01:12:20 - 01:13:35)
Revealing mistake: Before Interceptor's explosion, in the close-up it's very apparent that it's not the real Interceptor. Some examples are, no rigging at the stern-most mast, at the railing there are no belaying pins with or without all the lines hanging from them, there are no cleats with or without lines and at least two of the swiveling mounts at the stern for the swivel cannons aren't there. (01:30:40)
Deliberate mistake: Jack wears one pair of boots throughout the movie; however, the heel has at least two discernible heights, including the ones worn in the underwater close-up. One kind is worn by Tony Angelotti (Johnny Depp's stunt double) and the others are worn by Depp. When Jack steps onto the dock from the Jolly Mon and when he's balancing himself on Will's sword at the attempted hanging, he's wearing the higher heel boots. As Jack crawls across the broken mast chasing the monkey, and when he dives off the Pearl's plank, the lower heel boots are obvious. (01:34:40 - 02:06:30)
Continuity mistake: Jack and Will duel on the cart and in a side shot, the FIRST time Will crosses his two swords in front of him below his waist, the blade in his left hand is on top of the blade in his right hand, then in the following front shot, the blade in his right hand is now on top of the blade in his left hand. (00:25:15)
Revealing mistake: During the attack on Port Royal, Will crosses his axe (left hand) and sword (right hand) overhead to block a pirate's blow and then proceeds to slice that pirate across his abdomen. Yet in the previous shot, in which another pirate with a cap stabs a man who is leaning against a stone wall, we see Will in the background on the left of the screen, having stabbed that pirate in the abdomen already. Obviously cut and the takes were edited out of sequence. (00:31:20)
Continuity mistake: There are two shots of an unconscious Mr. Brown and the area around him, when Jack and Will approach him. Just before and after Jack grabs the red hot sword out of Will's hand and tosses it, Mr. Brown is seen behind Jack. In these shots Mr. Brown's placement is different in comparison to the tools above him on the ledge. Also in this shot, the tools on the floor to his right in the earlier shots, are not in the same place either. When Will says, "I practice three hours a day so when I meet a pirate, I can kill it," the actual tools to Mr. Brown's left are different. (00:21:05 - 00:24:20)
Continuity mistake: At the dock in Port Royal, in the close-up as Jack makes his escape from the Marines, he is standing on the beam as he throws his shackle chain over the rope. The ledge to his left, just under the rope, has a metal support that is flush with the wood's edge. In the next wide shot as Jack starts his descent down the rope, the ledge and its metal support are not the same as in the close-up, they are obviously very different. (00:20:10)
Deliberate mistake: After Will and Jack swing aboard Interceptor, Will cuts four lines from the belaying pins on Interceptor, that lead up to Dauntless and each line snaps back. As Interceptor pulls away though, we see other lines that are still connected to Dauntless, but then the shot cuts away. Because of a mishap during filming, it was the only shot Director, Gore Verbinski had of Interceptor pulling away from Dauntless. (00:47:05)
Continuity mistake: After her anchor is lowered, there's a front shot of Interceptor as it splashes wildly and a crewman that is dressed as Will is seen up on the port side of the rigging. After Elizabeth shouts, "Let go!" the crewman dressed as Will is up on the rigging, but now he's on the starboard side of the rigging. This is not a flipped shot, the sails are different in both shots too. (01:24:25)
Continuity mistake: Aboard the Interceptor, after Elizabeth lifts the hatch and comes up on deck, Anamaria says, "The Black Pearl. She's gaining on us." In the very next shot of Elizabeth, behind her on deck is the crewman with the tan hat. In the next shot as she looks out towards the Pearl, up at the top of the rigging are two crewmen, one of them is the same crewman that was just on deck in the previous shot. He's the one who stands on Cotton's left in Tortuga when Jack inspects the "able-bodied crew." (01:21:25)
Continuity mistake: At Jack's hanging, as the official says, "Impersonating an officer in the Spanish Royal Navy," in this far shot, we see the scaffolding and the Marines walking on wall behind. In the next shot, he says, "Impersonating a cleric of the church of England," and we still see the Marines. Then in the next shot, a close-up of Jack, we also see the Marines. These are successive shots, yet the Marines are NOT in positions of continuous walking. (02:05:05)
Revealing mistake: When Will opens the door to the blacksmith shop, on his immediate left outside, there is a stone wall with a plaque on it. That same plaque can be seen hanging high up over a doorway across the courtyard from the blacksmith's shop, when Jack goes into the shop earlier. The wall and plaque were added later, to that shot of Will. The plaque should not be able to be seen so closely, at that angle and distance, in the shot of Will opening the door. (00:20:40 - 00:21:55)
Revealing mistake: When Elizabeth falls down from the cliff, with her hat and scarf falling over her, you can see it is definitely not Keira Knightley, as the stuntperson's face is perfectly visible. (00:15:05)
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