Deliberate mistake: Spoilers! When Black Manta is defeated, he is knocked unconscious and tumbles down a rock face after his helmet explodes on his face into the waters by the shores of Sicily. These currents and waves at best would have carried him to the rocks or the beach, leaving him on land or near it. However in the after credit scene he's somehow found out in the middle of the ocean on a broken drift wood. He would not have been carried back out to sea like that.
Factual error: An M203 round arms at between 14 and 27 meters, and produces a ground burst that causes casualties within a 130-meter radius, and has a kill radius of 5 meters. Even if it did work all 3 would be dead. (00:18:35)