Plot hole: In the beginning after Flint buries the treasure, he kills all the men that are with him. The pistols he has are one-shot pistols, so there's no way he could kill 14 men using only two one-shot pistols.
Plot hole: Why is that shark machine even there? The only reason it's there is to help the plot, and I don't see how it is of use to anyone in the corporate world. If the shark just ejects the fish it turns into fish heads out to sea, there is too much chance they will be ruined by carnivorous fish or weather before they are picked up. And fishing companies should know better.