First time we see Therese, she has right sided hemiplegia and aphasia both consistent with a left brain infarct. When she is pulled to shore, her hemiplegia switches sides and for the rest of the movie she has left hemiplegia.
At 41:47 the bearded man gets up, takes off jacket, and walks to bar carrying the jacket over his arm (the chair at his table that he just left is empty). In the next few seconds, he asks two women to take his photo and his jacket is at the chair/table he had just vacated to go to the bar.
At 2:15:00, it is apparent that Abigail and Yaya are at some height above the sea level, but at 2:21:30, they are shown at the seashore.
At the beginning of the cruise, the chief stew is telling the employees that if any passenger asks for an "illegal substance" or "a unicorn" then "yes, sir, yes, ma'am" they are to provide it which is absolutely false. Maritime law prohibits providing ANY passenger an illegal drug, whether at sea or docked.
The 24-person enclosed lifeboat would have an inventory of food, water, medical supplies for 24 people for a minimum of seven days. In the movie the supplies in the boat wouldn't last a single day. Most importantly the boat would have at least one portable water-proof satellite phone. However, it's not unheard of for cruise companies to cut costs or generally be careless about the state of the lifeboats.
During the fashion show, when everyone is asked to move a seat to the left, there is a pan following the whole audience standing up and moving. If you look closely, you can see a single seat not taken in the middle of the row, making it unnecessary for Carl to be pushed off at the edge as the moving "one seat to the left" would have stopped there. However, it makes sense for everyone in the audience to simply obey the usher, and that seat could have already been taken or the usher didn't spot/care about it.
The Captain is flipping cards, with Dimitry guessing the color. If he guesses wrong, he has to drink. The last card that The Captain flips is a red ace. Dimitry guesses red, and The Captain tells him he has to drink. However, both of them are so intoxicated by that point that it hardly matters what color actually shows.
All through the captain's dinner during the storm while the boat is supposed to be rolling, the liquid in glasses stays level and glasses, plates, and silverware do not slide around or off the tables.
When the captain and Dimitry are talking through the intercom, there are several shots that are very clearly just moving the camera to simulate the ship being rocked, instead of the room really moving. This is apparent through the liquid in the captains glass, which stays level the whole time.
Although Dimitriy is Russian, he says "Lord's Prayer" in Croatian at 01:32:32.