Changes from the Book
The changes in this episode are made solely for time purposes, such as the only consequence of the press exposure is the meeting with Professor Calculus, resulting in Thompson and Thomson never visiting his residence alongside Tintin and Captain Haddock. In addition, Tintin has a smooth voyage in the Shark-proof submarine as opposed to the original book where he initially gets into peril when the vehicle is snarled with seaweed, leading to Haddock and Calculus coming come to his aid. Tintin is also the only one who does the diving during the treasure hunt rather than Haddock and one of the detectives also having a go, and it is Tintin who finds the cache of Jamaican Rum which Haddock only takes the discovery of calmly unlike in the original book. Furthermore, the treasure hunters never return to the island to dig around the large wooden cross because of the mistaken idea of where the treasure could be located, since Tintin comes to realize why that would be useless while returning from the island from episode's only landing. The scenes where Tintin and Haddock arrive and find the remains of Red Rackham's treasure at Marlinspike Hall and the opening of the maritime gallery at the same location during the end of the original book are also removed.
More minor changes made in this episode include Calculus during his first meeting with Tintin and Haddock did not mention to both that he is a little hard of hearing, which he would only later mention in the TV episode adaptation of Destination Moon when he uses an ear trumpet. In addition, Haddock does not write a message on a wall to tell Calculus that they are not interested in his invention, the Captain simply marks an "X" on the crate containing the submarine assembly to account for why Calculus stows away anyway and for the animators to avoid having to make multiple written translations for each language used. The mentions and appearance of Thompson and Thomson going on holiday at a farm is also removed.
- Colin O'Meara - Tintin
- Susan Roman - Snowy
- David Fox - Captain Haddock, Sir Francis Haddock
- Wayne Robson - Professor Calculus
- John Stocker - Detective Thompson
- Dan Hennessey - Detective Thomson