In the movie Dunkirk, how does the shell-shocked soldier end up alone on the upturned ship? The previous night he's shown to be ferrying soldiers to the beach. Suddenly he's sitting all alone over a boat in mid sea?
Is there an explanation to what happened?
The events of the film are not exactly chronological. The subplot of the soldiers (called "the Mole") takes place over the course of a week, whereas the subplot of the people on the boat (I think it's called "The Sea") happens in a day.
Thus, this soldier hasn't suddenly jumped from one boat to another, there's at least the amount of time from the previous night to the next day's afternoon for him to have gotten aboard another ship, and for that ship to be sunk. There might even be 2-4 days between the two events. Soldiers were being evacuated from Dunkirk the whole week, there could have been a half dozen or more ships we never saw in the film carrying troops off the beach.
Note also that the English channel can be crossed twice in a day (you can almost see 'home' from Dunkirk). So no matter where in it you are, you're only a few hours from shore.
This is explained at Wikipedia
They encounter a shell-shocked soldier on the wreck of his ship, the sole survivor of a U-boat attack, and take him aboard. When he discovers that Dawson is still sailing for Dunkirk rather than returning to England
The sole survivor of that shipwreck mentions that a U-boat attack sunk his vessel. This implies a torpedo strike, which as we see later in the film can cause a ship to founder in minutes. It's not unreasonable to expect a very large percentage of the crew to perish in such an attack - especially if it happened at night when there would have more people below decks than outside.
