That falls under Declaration of Details. Anyone may declare details at any point at the cost of a Fate point - I do have a veto, but if the details being declared are interesting and make the game more fun, I won't use it. If it's borderline, there may be a roll involved.
If the details are just local colour, then it won't cost a Fate point; if they're relevant to the situation, then it will.
Buck's "Toured the world" aspect does give him little a bit more leeway when it comes to declaring details about Hawaii than the others would have; but anyone can still declare details.