Other mistake: Even though Ryan was warned earlier that the water was so cold that you could survive in it for only four minutes, he doesn't even shiver while drinking coffee in his wet clothes inside the Dallas. This after plunging deep underwater from his fall from the helicopter and then waiting to be rescued and brought aboard by the diver.
Other mistake: When the sub is ordered to turn right, Ramius is seated facing forward and tightens his seat belt. When the sub makes a tight right turn, his coffee cup slides the wrong way. (01:00:01)