When Captain Haddock rescues the "Shark" submarine (Operation Rescue), there's nobody in the submarine (when it should be Tintin and Snowy).
The latitude/longitude for the sunken treasure ship, on a hidden note discovered by Tin Tin, is actually a spot deep in the Sahara Desert in Mauritania (20deg. 37min. 42sec. N by 10deg. 52min. 15sec. W).