The Wreck of the Mary DeareGoofs
When Patch and Sands jumped off the salvage ship dressed in SCUBA gear, they already had their goggles over their eyes and the mouthpieces in their mouths. Seconds later they were swimming on the surface with goggles on top of their heads and mouthpieces out of their mouths, and putting those back on as they went underwater.
Errors in geography
Captain Patch claims the Mary Deare was steaming from Portugal into the English Channel (headed North) when she encountered the sabotage. His plan was to beach the ship in the dangerous area south of the Channel Islands off the coast of France. Patch's course shows a 90 degree turn to port, which would put the wreck on the English coast. The course should have been a hard turn to starboard.
Patch and Sands enter the sunken portion of the Mary Deare using SCUBA equipment and are followed by Higgins and crew members by observing their underwater lights. Close-ups show large amounts of bubbles from the SCUBA in the underwater shot but no bubbles seen by Higgins on the surface, which would have made their locations very obvious.