Revealing mistake: When Jack, the monkey, runs off with Ragetti's false wooden eye, the pirate's eye socket does not look empty in specific shots, only covered by a contact lens. (00:41:10)
Continuity mistake: At the edge of the cliff, in the first overhead shot, when the four men lift the coffin its "head" side is nearest the water. However, in the next shot the "foot" side is nearest, before they throw it in the water. (00:05:30)
Continuity mistake: When Lord Beckett is trying to convince Will Turner to go after Jack Sparrow, he picks up a red hot poker from the fire and says that they've marked each other. The shot cuts to Will who asks simply "How did he mark you?" at which point the shot cuts back to Beckett and the formerly red-hot poker is already now a much cooler black. Glowing hot iron does not cool that quickly in air. (00:09:30)
Revealing mistake: Elizabeth says."Oh the heat." You can see the exact spot where she is going to fake faint, from previous takes. (01:44:35)
Continuity mistake: In the scene where Jack meets Bootstrap, Bootstrap's hands are filled with barnacles but when he touches Jack's hand to give him "the black spot" his hand is suddenly blue with no barnacles. (00:13:50 - 00:15:30)
Continuity mistake: When captain Jack Sparrow gets slimed by the Kraken, Jack's hat lands on deck, slime-free. In the next shot, the hat is in a glob of slime. (02:09:30)
Continuity mistake: When Norrington, Elizabeth and Jack find the chest they wipe some sand off and there are black parts of the chest visible. When they pull the chest out of the ground, all the black bits are gone and is covered in sand.
Continuity mistake: When Jack, Norrington and Elizabeth find the chest, the amount of flowers visible changes instantly. (01:41:20)
Continuity mistake: When the two women put the necklace around Jack's neck they are stood next to each other and are close enough that they are touching each other as they put the necklace on. When the shot changes they are stood around 1ft away from each other. (00:31:20)
Continuity mistake: When Jack first gets slimed, in the shot of him to the side there is a glob of slime on his chest dripping to the floor. When the shot changes to in front of Jack, this glob of slime has gone and is replaced a second later. (02:09:20)
Continuity mistake: When talking to Bootstrap for the first time, Bootstrap is saying how he was thinking about any chance of escape he would take it. When he's talking, the bone in Jack's hair switches from uncovered to covered between the long and close shots. (00:15:10)
Continuity mistake: Beckett tells Elizabeth that she needs to up her offer. She replies by cocking the gun that is under Beckett's chin. Beckett then walks with the gun under his chin to his desk. However, when he arrives at his desk, the gun is now by his right cheek. (00:28:50)
Answer: The jar was to put Davy Jones heart in. He can't touch dirt ever again since he failed to keep up his duties which means he wouldn't be able to get his heart back.