Deliberate mistake: The baddies somehow manage to place the net under the two humongous ships by simply digging with their shovels in a matter of minutes, when they would need a bulldozer and several hours instead.
Deliberate mistake: The whole airplane scene with the heavy cargo flying away and hitting the heroes without harming them plus them jumping and standing on the flying cargo defies the laws of gravity, physics and common sense.
Answer: Jo and her mercenaries were at the wrong island, It's when they saw Drake go past them in a speed boat, and not to the island they were on, that's when they realised they had been tricked.