When Barbossa is chasing the Interceptor, as he is shouting commands, in one shot his teeth are perfectly white, while in the rest of the movie they are decayed.
(at around 8 mins) When he first shows up in the movie bringing the sword to Governor Swann, Will Turner is almost clean shaven (just a trace of a little mustache). His next scene (at around 22 mins), at the blacksmith shop --- which in the movie happens at the same day, maybe an hour later --- Will has a little goatee and almost full mustache.
(at around 10 mins) At the beginning when Jack is standing on the sail of his sinking boat, he prepares to step onto the dock by raising and extending his right foot out. The next shot shows his left foot taking the first step onto the dock.
(at around 45 mins) When Jack and Will board the Dauntless after walking under the water with the rowing boat over their heads, by the time they have climbed onto the deck and announced that they are taking over the ship their clothes are bone dry.
(at around 2h 10 mins) After she puts Jack's coat on him, Anamaria takes her hands off his shoulders twice.
(at around 27 mins) Elizabeth Swann's maid fills a bed warmer with red-hot coals and then places the warmer at the feet of Elizabeth, who is lying in bed. That's not the way bed warmers were used. They held warm, not red-hot, coals, and were placed in bed before one turned in and removed before the sleeper lay down. If used as shown in the movie, they would have barbecued one's feet.
(at around 45 mins) When Jack and Will walk underwater towards the ship they intend to steal, they are holding an upturned rowing boat over their heads to trap air, allowing them to breath. This would be impossible in real life, since not only is the boat made of wood (which floats), but due to the upthrust of the trapped air, Jack and Will would need to weigh several tons between them to keep the boat down.
As Elizabeth and the medallion sank toward the sea floor, it was suspended weightless in the seawater. Aztec gold would hang almost as heavily as it does on dry land.
(at around 27 mins) Bed-warming pans shouldn't be necessary in a tropical climate.
(at around 21 mins) Jack Sparrow offers the chains of his handcuffs to the wooden teeth of a cogwheel in a mill. Wood is softer than metal and could not have broken the chain.
(at around 1h 30 mins) Captain Barbossa, after telling Elizabeth to remove her dress before being deserted at the island, lifts the dress up to his face and says, "Still warm." The pirates are not supposed to feel anything, but it is possible that he was being facetious.
(at around 39 mins) When Elizabeth is on the Black Pearl, she holds the medallion over the water in order to prove that the pirates actually wanted it. Though the pirates can walk underwater and suffer no ill effects, they still jumped when she pretended to drop it because of the instinct to prevent it from being lost. Breathing underwater is not a natural human state, and they likely still think mostly as humans. Furthermore, a tiny piece of gold adrift in the ocean in the middle of the night would not be easy to find, even for the undead.
Throughout the entire movie, we are led to believe that whoever possesses one of the cursed pieces of gold becomes one of the undead. So the question becomes how come Elizabeth wasn't part of the undead when she possessed one of the pieces of gold all those years? Answer: It's only people that take the gold from the chest directly. Otherwise Will would have also been undead as a boy since his father passed it to him, not to mention an untold number of undead merchants, bartenders, prostitutes, etc. who received the coins as payment. Jack only became undead towards the end because he took one directly from the chest.
Will has a tattoo on his wrist which is visible in some shots. We are not told that Will is free of tattoos and the fact that *we* know it to be an "elvish" nine is of no consequence --- it's just a pretty pattern.
(at around 29 mins) When the Black Pearl attacks Port Royal, huge explosions occur wherever her projectiles impact. Cannon in the age of sail did not use explosive shells.
(at around 1h 55 mins) When Norrington arrives on the HMS Dauntless to fight the cursed pirates, some of the naval personal are fighting no one because the CGI skeletons weren't put in.
(at around 20 mins) When Jack had just escaped and is flying around in circles around the pole, the soldiers are told to shoot him. Many of them continue to shoot, without reloading.
(at around 1h 23 mins) When the Pearl is chasing the Interceptor both ships go full wind. Therefore, flags on both ships are flown back as though the ships are propelled by something other than the wind. When a ship is driven by the wind, the flags will be flown in the direction of the wind which in full wind will be from stern to bow.
(at around 49 mins) After Will and Jack commandeer the Interceptor, the ship is viewed from above, sailing on a beam reach (a point of sail in which the boat is at 90 degrees to the wind). When Jack knocks Will off the ship with the boom, he jibes the boat, causing the sail to shift positions suddenly. In order to do this from the previous position, he would have had to turn the ship almost completely around. This would have taken well over a minute. Jack did this in less that three seconds. The sail is also filled to the wrong side while it sweeps Will off the deck.
(at around 25 mins) There are several points during the sword fight in the blacksmith shop where there is an obvious stunt double for Will, such as when he somersaults over the pole --- the double has a much higher hairline than Orlando Bloom.
At 2:05:25 when they're reading the list of charges, you can see a female extra mouthing the words. This is most likely because they've done this take so many times and she wasn't thinking about the optics, or didn't realize how prominent she'd be in the shot.
When Elizabeth is brought aboard The Black Pearl, the deck is abustle with activity, and the waters around the ship are still; there is no indication that they are under any sort of direct fire from the fort.
Barbossa is seen holding a Granny Smith apple throughout the movie. Granny Smiths originated in Australia in 1868, around 150 years after the events of the film.
The films place the Governor's Mansion in Port Royal, but that city was almost entirely destroyed by an earthquake in 1692, at which time the capitol of Jamaica was moved to Spanish Town. The signature of George I on Norrington's orders dates the films to at least 22 years later.
(at around 1h 45 mins) "Bob's your uncle" the British catch phrase, meaning all will be well or all will be taken care of is thought to refer to Prime Minister Lord Robert Salisbury who appointed his nephew to be Secretary of Ireland in the 1890s.
All the Royal Navy officers seen are wearing uniforms that would not be introduced until 1747.
Norrington's orders were signed 'George R,' indicating King George I of England. This dates the film to between 1714 and 1727.
(at around 49 mins) The word "Scallywag" which is used to refer to a fellow pirate, is in fact only invented in the 19th century (after the American Civil War as a name for white southerners who collaborated during the reconstruction).
(at around 16 mins) When Jack tears the skirt of Elizabeth's dress off underwater, the loud ripping noise is heard of dry fabric being torn.
(at around 49 mins) When Will draws his sword on the Interceptor and tells Jack that his father wasn't a pirate, the sword makes a metallic scraping noise, despite being tucked in his belt without a sheath of any kind.
(at around 23 mins) [DVD 2-Disc Edition] In the blacksmith scene when Will says he threatened Elizabeth, Jack replies "Only a little." in one audio version. In another audio track, he says "Just a little bit."
(at around 11 mins) At Commodore Norrington's promotion ceremony, the troops are given the command "right about face," which they proceed to execute. As the camera changes angles, they have not completed the command, but you never hear the sound of their feet completing the last step of the maneuver.
(at around 2h 10 mins) Just as Jack says, "On deck, you scabrous dogs," to the very left edge of the screen over Jack's shoulder is a grip crew member with a tan cowboy hat, white short sleeve tee shirt and sunglasses, just standing there looking out to sea.
(at around 1h 40 mins) When the Commodore and Jack are discussing how to attack the cave and the Pearl, the movie pans out to show the two small boats. The boat that has Jack and the Commodore in it, if you look to the right in the water you can view a green diver's fin that comes out of the water.
(at around 30 mins) During the first attack of the Black Pearl, the air-rams that catapults the stunt men (to make it look like blasts of explosives) are clearly visible in several shots.
(at around 9 mins) When Captain Jack's boat is taking on water, when we first meet him, water splashes onto the camera's lens after he throws water out of the bucket he is using to bail (lower right corner).
When Jack Sparrow is about to walk the plank, and is speaking with Barbosa, there are several shots where you can see metal scaffolding behind Jack.
Port Royal, Jamaica, is built on a low spit of sand south of Kingston Harbor, nowhere more than about 10 feet above sea level. The movie set has it built atop hundred-foot basaltic cliffs.
The Royal Navy did not station any 100 gun ships of the Line in the Caribbean. The ships were simply too large and deep drafted to be of much use in those waters. The English bases in the area were incapable of supporting ships that size. And the Royal Navy only had six such ships world-wide at the time of the film.
(at around 1h 8 mins) The chest of cursed Aztec gold, which Cortez was said to have taken from Mexico, depicts four representations of the primary image of the Sun Gate from the Tiahuanaco civilization, outside La Paz, Bolivia.
When the Governor opens Elizabeth's window, we see the point of land from the same angle as Jack sees it standing atop his sinking boat's mast.
When Jack first sails into Port Royal, there is a shot from behind Jack, looking toward the front of the boat, and there is land clearly visible across most of the field of vision. After Jack jumps down, you see him (from a side shot) begin walking toward the back of the boat. The next shot is again looking towards the boat's front from the stern (which cannot be disputed because Jack is completing the strides from the previous shot) and there is no land visible at all.
(at around 1h 50 mins) During the battle scene at Isla de Muerta, Commodore Norrington and his men on the rowboats does not hear the gunfire on board the H.M.S. Dauntless. However, when the wounded sailor on board the Dauntless rings the bell, we see a shot of Norrington looking towards the ship then a shot of the ship with gunfire clearly audible and echoing through the night. If it was audible at this point from this distance, then it should have been audible since the first shots were fired and thus Norrington should have noticed them without the need of the bell.
At the beginning of the movie when young Will Turner is found floating in the sea, it is quickly discovered that his ship had been destroyed and was burning up on the surface of the water. There is no way that the crew on Elizabeth's ship would have missed the blaze in the otherwise still waters.
(at around 36 mins) During the siege on Port Royal, two cursed pirates from the Black Pearl find Jack in the jail. Later (at around 1h 15 mins), during the confrontation on the Isla de Muerta, Pintel sees Jack and says "you're supposed to be dead." This means the pirates who entered the jail never told Barbossa or any other pirates in the crew that Jack was actually alive and nearby locked up. It's extremely unlikely that they not only would not tell any other crew members, but not tell Barbossa who led the mutiny against him and left him for dead.
When Barbossa tells Elizabeth about the curse, he talks about how he and his crew gradually started to realize they were cursed. (Loss of taste, smell, not being able to feel etc). Which implies that the "skeleton in the moonlight" part of the curse was also something that became apparent over time.
Yet when Jack takes a coin from the chest, subsequently cursing himself, he turns into a skeleton in moonlight even though he took the coin only a few minutes prior.
The crew of the Black Pearl needs Will Turner's blood to lift the curse because they killed his father. This would be unnecessary if Will's father never partook of the gold, and if he did, he would be subject to the curse himself, which is that he cannot die.
(at around 11 mins) The British military expression for people to stay away from a place is "Out of Bounds" and not the American "Off Limits." These are British troops, they would not have said "Off Limits."