Early in the film, Nady and Gibson meet up with a group of masked men in an abandoned concrete building. One of them jumps down onto a concrete table and scares Nady, who is wearing blue jeans. In the rest of the film, she wears gray pants.
(at around 45 mins) When Jean-Claude Van Damme is fighting in the rain, he kicks the pirate a few times, then does a spin kick. When he finishes and lands, he falls to one knee. A split second later, he is standing up.
The 40-foot boat never has more than two men on deck and four or five below decks, Freddy has a lot more men with him when Gibson catches up in Charleston. In addition to the cyborg and at least one "pirate" guarding her off-screen, Freddy is joined in one shot by another 13 pirates, after Gibson has already killed five. That's a total of at least 21 on the small boat.
In the final knife fight scene in the rain, Gibson sticks the knife in Fender's upheld blocking forearm with a downward overhand stab. In the next scene, when the knife is still in Fender's forearm, his hand is holding the knife in a sideways grip with the palm down, opposite of the grip during the stab. The knife only goes in about an inch or so, but it's shown buried to the hilt.
When Gibon's face gets cut during the final knife fight scene in the rain, the downward slash is shown several times with no effect. The final time, blood already streaming down the face when the knife strikes.
When Pearl tells Gibson that she can trust him, the camera shows the same actress in close-up shots. When Fender walks over and stares at her, an animatronic lookalike of his former lover Mary is used.
In the first scene, when Pearl's protector is lying injured on the ground, he looks up to see Fender and his whole crew walking towards him in slow-mo, with huge flames billowing behind them. The flames are coming out of a hose-like apparatus that barely stretches the length of all members of the group, with fire coming out of the top.