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.
Suggested correction: The water is tidal. If the tide was going out, the current would take him out to sea.
There are hardly any tides in the Mediterranean Sea http://scienceline.ucsb.edu/getkey.php?key=995.
Question: Why didn't they move? Surely they could've hidden in one of the other states mainly a landlocked one like Iowa, Nebraska, or Kentucky, as in not near an ocean.
Answer: Yes I mean as in his father and mother should've moved, not the Atlanteans.
They both obviously love the ocean very much, and it might have been to hard for them to live away from it. Call it a false sense of security if you will.
Answer: If you are talking about the Atlanteans, their entire civilization sunk into the ocean. Instead of leaving it, all that history, culture and technology, they adapted instead. They didn't want to leave their home and be exiled forever. A lot did go and live in other areas of the ocean but by that time humans had taken over on land, and they didn't want to interfere, nor did they need to by that time.
I think the question is asking why Arthur's parents didn't move. Why, knowing that people from Atlantis are hunting you, would you continue to live near the ocean?
Question: How did others find the trident's location? We know Arthur is the first person to see the clue to the trident's location, so why are there dozens of skeletons of past victims, how did so many others magically stumble across the trident?
Answer: You said it yourself some might have stumbled upon it, others could have used the map, which is why it was hidden in the first place.
How could they use the map when Arthur was the first to find it...quite frankly to stumble on it is impossible, you would have to randomly travel to the trench, go through the entire kingdom, see a tornado of death and decide to go in, get spat out and not eaten, get to shore, check behind a waterfall and follow it down...bit much?
Question: Did Aquaman kill all Black Manta's crew at the start? As far as I can see he just knocks them out, but they don't seem to leave. If they die, why is he so upset about the guy's dad, when he left a half dozen to drown?
Answer: As far as I can see, Aquaman didn't care if the pirates died, including Kane's father. When Kane begs Aquaman to help save his father, Aquaman just glares at Kane and says, "You killed innocent people" and abruptly leaves without helping. Aquaman then saves the Russian crew but leaves the sub and pirates to sink. All of this explains why Kane becomes Black Manta (because he hates Aquaman for leaving Kane's father to die). But, as far as Aquaman was concerned, the pirates got what they deserved.
Answer: It was an accident, while trying to stop Black Manta's crew, Aquaman's battle caused a lot of damage. Which made one of the bulk heads blow and pinned his father down. He believes if Aquaman had let them siege the submarine and not interfere, his father would be alive.
Little correction to the answer: Kane's father fired two mortar rounds in the sub's torpedo magazine (which somehow, amazingly, did not detonate the the whole sub). The first mortar struck Aquaman dead center without killing him and everyone else in the room. The second mortar damaged the torpedo rack, dislodging a torpedo that pinned Kane's father against the bulkhead.
