At the 10 minute mark as the trawler is hit by a storm. Medium shots of the deck show that sails are rigged, while cuts to a long shot of the entire boat show no sails, then back to another medium shot with the sails up again.
The wounded Conrad gets soaked through then a close up of him shows him to be perfectly dry.
At the very beginning, a container is lowered into the hold and men start loading fish into it. A few seconds later, the captain says he is going ashore. A quick cut and as the captain is leaving, the container is now being hoisted out fully laden with fish. That was much too quick for the fish to be loaded.
A crewman states that the mystery vessel must be Danish because the only remaining square riggers are Danish. In fact, Germany also had square rigged ships during this period. One became the American Coast Guard "Eagle" and one the Russian "Tovarisch" as war prizes taken following World War II.
A German sub sweeps the schooners deck with a searchlight except that the sub would't be high enough in the water to do so.
When the vessel is sighted, a crewman calls out, "Schooner dead ahead". As the vessel is square rigged, it cannot be a schooner which is fore and aft rigged. No Grand Banks fisherman would ever have made this error because schooners made up a large part of that fishing fleet.