Perhaps a mild one, but notice how Jack always seems to stagger around semi-drunkenly? He moves on land as if he's still on a ship!
A commonly remarked-on affliction of sailors in reality as well as fiction, especially in the days when ships were much slower and had no compensation for this action. It's known as having 'sea-legs' (once it sets in, one gets far less motion-sickness.) However, in reality it usually stops within a few hours of coming ashore, whereas with Jack it seems permanent.
Given that this is Jack, is it surprising he would fake a permanent case of sea-legs? In fights he seems to be moving normally, except for when he would benefit from sea-legs.
The original theme park attraction featured Blackbeard attacking a coastal settlement aboard his ship, the Wicked Wench. Around the time when Dead Man's Chest was released, the ride was updated to include characters from the films, and Barbossa replaces Blackbeard as the Wicked Wench's captain. Come On Stranger Tides, which features Blackbeard as the villain, and at the end of the film, Barbossa kills Blackbeard and takes command of his former ship. Looks like Disney was doing some foreshadowing...
On a related note, supplemental materials for the films state that the Black Pearl was originally christened the Wicked Wench. So, when Barbossa is the captain of the Wicked Wench in the theme park attraction, he's in his rightful place as captain of the Black Pearl!
It makes sense that Davy Jones has a completely bizarre accent- he's immortal, and has been around long enough to become a legend, and has very little contact with the world beyond his ship. He could easily be hundreds or even thousands of years old. His first language has either died out or evolved to the point that modern speakers sound completely different.
He's around for just a couple of centuries. Davy Jones is not an ancient name, and his clothes, seen when he temporary reversed to his human form, are of 16 or maybe 17 century fashion, not much earlier and definitely not thousand-years old. And accent... Well, as Word of God states, Davy Jones is Scottish. And really, he had very little contact beyond his ship, so his natural accent could change during all those years with the same scum all around.
Throughout the series, sea turtles are constantly brought up as a Running Gag by several pirates. The name of the pirate port, Tortuga, is Spanish for turtle.
In Curse, as Jack palms the cursed coin, Will is watching intently and has a brief look of realisation. As he's not surprised at all when Jack later frees him and is also cursed, this is presumably the point at which he worked out what Jack's plan was. Supported by his instant, if clandestine, support of Jack's negotiations with Barbossa.
In World's End, there's a similar moment between Jack and Will whilst meeting with Beckett and Davy Jones. When Elizabeth tells Will that freeing his father is a lost cause, Will replies that "No cause is lost, so long as there's one fool left to fight it", and glances significantly at Jack, who grins back - Again, Will's worked it out and is offering help.
Take a good look at the Pirates of the Caribbean skull logo. Red scarf, plaits, the coins, the beads - yep, that's Captain Jack Sparrow. Or what remains of him. Just to drive the point home, attached to the plaits is a Captain Jack Sparrow voodoo doll.
Averted if you assume it's Captain Jack while he was under the Curse himself.
Dubious. Even under the curse, Jack's skull was covered by remnants of withered flesh. Most obviously, he still had eyeballs.
This is interesting. On the Blu-Ray main menus for the first three movies, the skull from the logo seems to act as a narrator of sorts. So the undead skull of Jack is telling his story generations later. Interesting.
Nobody seems to remember the Redshirt who fell off the Black Pearl in the third film while still in the world of the dead. He's going to drift in that sea for all eternity.
How about the pirate who got blown up from the inside in Curse? Governor Swann's encounter with a severed arm shows that the bits and pieces of the curse-bearers remain animated, so all those scattered, scorched bits were still conscious and trying to slither back together for as long as it took to break the curse.
Notice the voodoo doll hanging from the hair, yeah pretty creepy if you ask me
What about ol' Bill Turner? Why would Will want his father to continue suffering a Fate Worse than Death?
If you're referring to the curse on the Flying Duchman, it was stated somewhere that the curse was broken when Elizabeth was there when Will got his one day ashore plus the fact that he continued its duties. Bootstrap stayed on as a willing, free crewmember.
Also, ol' Boostrap was initially rescued by Davy Jones from a Fate Worse than Death strapped to a cannon at the bottom of the ocean. Being freed from service on the Dutchman might mean William the elder has to pass on to the realm of the dead if he leaves. Much better to make up for lost time with his son, both doing what they love doing best.
Speaking of the Pirates franchise, if you check out the Wikipedia page about Port Royal, it states at the end of the first paragraph, a number of horrors that descended upon the town starting and ending with two deadly earthquakes: one in 1692 and another in 1907. Fires, hurricanes, floods and epidemics were also in the mix. It almost makes some of the fates for the cast seem more pleasant than if Will and Elizabeth had gotten married and everyone lived out 'happy' lives in the town.