Looks like someone told Michael Douglas that the key to speak perfect Spanish was to pronounce all "n"s as "ñ"s? And people who learned their geography from the Hollywood movies has been convinced ever since that the name of Cartagena is Cartageña?
shareJoan didn't pronounce it with an ñ so I assumed they wanted Jack to pronounce it wrongly, maybe to show that he is not particularly knowledgeable about the area, or enhance the uninterested, uncaring loner character, or just to add realism - in real life people pronounce things wrong or make mistakes, eg. "has been convinced" (should be "have been convinced").
shareEVERYONE ELSE in the film pronounced it correctly, so Jack would have to be deaf not to have picked up the right pronunciation after a year-and-a-half in Colombia.
I always figured that, since he was the film's producer, Douglas simply pronounced it the way he damn well pleased.
That's what I always figured, at least. 😉