The Black family must have tremendous military and political power. Even accounting for game play and story segregation for building a civ at every single level, based on the enemies they are fighting (Circle of Ossus is well armed enough to occupy Havana and the Blacks are confident enough to launch an attack on an outpost of the Ottoman Empire away from their homeland) as well as the fact they have minimal oversight and orders from higher up suggests that the Blacks are an army onto themselves. A small scale version of an N.G.O. Superpower perhaps?
When the player gets to the Imperial Age, he gets the option of building a Capitol and researching three technologies that tremendously increase the gather rates for all sources of Food, Wood and Coin. Sounds awesome doesn't it? The names of these techs are, respectively, "Large Scale Agriculture", "Deforestation" and "Excessive Taxation". These three issues became real problems during the late 19th century and the 20th century, so, in a way, the player becomes the cause of agriculture spreading like wildfire, the loss of thousands of acres in woodlands and the fact that so many people became crushed under huge debts. "It's just a tech and it's just a game!" you might say. "I'm just improving my civ's gathering rates!" While this is absolutely true, the fact remains that not thinking about the consequences for these actions is exactly why many politicians of the 19th were responsible for the problems caused by Large Scale Agriculture, Deforestation and Excessive Taxation.
On a similar note: fishing boats can gather food from fish or coin from sperm and humpback whales. While gathering food from fishing site eventually exhausts the food from it, a whale as coin source is infinite! That's right: throughout a game, you can station a maximum of four fishing boats around a whale (and there is usually more than a single whale on the map) and have them gather coin uninterruptedly until you move them away from the coin source or they get destroyed. Needless to say, even though at first we thought we'd never run out of them, whales turned out to be a very finite source of coin as time went by.
Morgan Black is over 30 at the time of the Siege of Malta in 1565. John Black, his grandson, is in his 20s when the Seven Years' War breaks out in 1756. This looks like a pretty evident case of Writers Cannot Do Math until the end of the campaign, when it is revealed that while the Fountain of Youth was destroyed at the end of the first act, its water was still available and that Morgan (and probably Elizabeth) drank from it. Morgan is in fact still alive by the freaking 1840s, although as a very old man.
Aztec pyramids double as fortresses in III as in II. At first it looks silly but then you realize the Mesoamerican civilization's pyramids are not simple step pyramids but the average joe will have difficulty climing up the stairs. Add in archers barraging you with arrows and it becomes an impregnable defense.