Deliberate mistake: The East India Trading Company in reality, branded pirates with a 'P' on their foreheads, never on their arms, the way Captain Jack has it. It was deliberately decided to be historically inaccurate, feeling it looked better on Depp's arm. (Confirmed on commentary.) (00:17:20)
Deliberate mistake: During the pirates' attack on Port Royal, when they go about cutting and slicing, it is very obvious many times, especially in close-ups, that fists, weapons, etc., do not make contact, and the victims usually have a delayed reaction or react before actually being hit. This type of thing occurs numerous times aboard Interceptor, on Tortuga, and Isla de Muerta. (00:31:20)
Deliberate mistake: When Will is staring at Jacoby, another pirate comes up from behind him and hits Will on the head with a solid silver candlestick. The sound it makes when hitting Will's head is a sharp clang, as if it hit another metal, not reverberation. Post production thought it sounded more dramatic and funnier than a thud. (00:35:25)
Deliberate mistake: Not only is the angle of the moonlight that shines through Jack's prison cell window intentionally exaggerated to enhance the shots with Jack, doggy, Koehler and Twigg, but in relevant shots, the moonlight is not seen coming through the window or the broken wall. Nor is it reflected on the floor outside the cells or in the cell next to Jack, particularly in the shots from the dog's POV looking up the corridor towards Jack. (00:36:00)
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)
Deliberate mistake: After Barbossa takes the apple from Jack and throws it into the water, the sailing Interceptor is shown. Out on the edge of the bow are two men. One is dressed as Will, but it is neither Orlando nor his body double, Mark. The man behind Will is obviously not one of Jack's crew either. (01:21:15)
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)
Deliberate mistake: Throughout the entire film the metalic rasping 'ching' sound is unrealistically heard, even when drawing swords from something like leather holders. Some examples are, at the cave, Jack draws a sword hanging across the shoulder of one of the pirates, and throws it to Will, whose hands are bound. At Jack's hanging, just before Will throws his sword into the trap door to save Jack, Will draws his sword from the brown leather strap. This is obviously done for dramatic effect. (01:52:10 - 02:06:15)
Deliberate mistake: As was admitted on the commentary, the angle of the moonlight in the stateroom, which has a deep overhang outside of the doors, was deliberately vastly exaggerated, to enhance the shots with Governor Swann battling with the disembodied skeletal arm. (01:56:25)
Deliberate mistake: When Jack Sparrow and Will Turner take a rowboat and put it over their heads upside-down and walk on the bottom of the harbor (about 20 feet deep by the looks of it), wouldn't the rowboat rise to the surface? The amount of air trapped in the boat appears to be around 3-5 cubic meters, even at three that would provide plenty of lift to lift a boat twice that size and both people to the surface. This isn't even taking into account that wood and people are both fairly buoyant in and of themselves, even without the air pocket to aid. This scene is a direct homage to an earlier pirate movie, The Crimson Pirate, in which three characters do the same thing, hence this is a deliberate mistake.
Chosen answer: Because they'd have to find it. The gold may "call to them", but it obviously doesn't function as a millimetre perfect homing beacon or they'd never have missed the medallion years earlier when they attacked the ship carrying the young Will. Elizabeth drops it into the sea and they're going to have to spend what could be months trying to locate it - currents could take it well away from the dropping point. They've found the final missing piece; they're potentially just hours away from finally being cured. The last thing they want is to see it thrown into the sea.
Tailkinker ★
Well, if the crew was anxious to get the medallion then why did they act like they weren't interested in it before Elizabeth pretended to drop it?
Reverse psychology.
Ssiscool ★
What do you mean by reverse psychology?
By showing they are not interested in the medallion they are hoping Elizabeth will just drop it on the floor or chuck it to them as it's of no real value. However when she releases a bit of chain and the medallion drops, and the pirates lurch forward revealing that they really want the medallion and as such Elizabeth now has the upper hand in negotiations.
Ssiscool ★
I'm guessing Elizabeth wasn't fooled when the pirates showed disinterest in the medallion.
That's not called reverse psychology, which is used to encourage someone to change his or her mind. Doesn't work with a threat. They are feigning indifference to hide the importance of the object.
lionhead
They didn't want to give her an advantage over them. Pretending to not care about the coin would make Elizabeth think that the coin is worthless and cannot use it to barter a deal.