There are many inconsistencies with the opening scene of the episode. The water is seen to be shallow at times (too shallow for a cruise ship), then the swimmer is seen from below at a great distance; the swimmer and the life preserver are seen near each other from above, then the swimmer is seen from below with the life preserver nowhere near him. Reflections in the water of a shoreline or docks in the background are visible in close-ups of the swimmer but in long shots it's open ocean.
The Captain of the cruise line wears Army/USMC "Captain" insignia. A captain of a cruise liner would either wear four gold stripes, which is the Navy insignia for "Captain", on each shoulder or even admirals insignia. But not Army/USMC insignia
In the flashback of the victim climbing the stairs and discovering his teenaged stepdaughter with a member of the crew, the jetty off the bow of the Queen Mary (where this episode was filmed) is visible, even though the ship was supposed to have been at sea.
The cruise ship was obviously stationary during the shark attack. The ship does not move forward, by the swimmer and sharks.