The number of lifeboats being towed often changes from shot to shot.
In Part 1 at the 13:15, scene in the Dry Dock,
The Bow of a ship can be seen in the background,
this ship has a bulbous bow. BUT bulbous bow were not incorporated in ship construction until 1963.
Thomas Mortimer is presented as a Jr. Third Officer and is wearing 3 stripes on his shoulder patches. Jr. Third Officers only have 1 stripe.
When Hilda is on the Laconia discussing her baby, she says that she is five months old. When she is on board the U-boat, she says that the baby was seven months old.