Factual error: When they go into the water, they put mouthpieces in, but, a few times, they talk to each other, which is impossible with mouthpieces in.
Factual error: The dive crew says they are using rebreathers as dive gear. Rebreathers do not produce bubbles, but most of the underwater shots show the team making bubbles.
Factual error: An underwater scooter explodes like dynamite, collapsing the tunnel early in the movie, but underwater scooters are electric and designed not to kill divers. (00:29:12)