Continuity mistake: On the derelict boat, Humphrey invites Dwayne to do some sanding together, but Dwayne has a counterproposal. Humphrey listens to it with his hand on his hip, away, on the hip again. (00:21:15)
Continuity mistake: Dwayne points his finger at JP telling him his former superior said "a policeman can't have any weaknesses." Reverse shot, and Dwayne's hand is nowhere in sight, but it is a moment later. (00:16:30)
Character mistake: The rap sheet of Laura Hagen's dad says that he served "half of an 12 years sentence." An twelve? (00:15:50)
Continuity mistake: Dwayne mentions enlisting the help of the Saint Marie diving school. At the following cut, his shirt is more open, revealing more of his trademark tank, and he is holding the notepad where it would have been visible in the close-up. (00:09:55)
Continuity mistake: Humphrey and Florence go back on the boat after the preliminary interview. Florence is on the phone with the Coast guard when she gets on the boat; the phone is on her left hand, and the right hand is occupied by the notepad. When she tells Humphrey the coast guard's report, they have traded places. (00:09:20)
Continuity mistake: Laura Hagen is back in the cabin to retrieve the sample bag she forgot. The bag was under a map on the table, which she moves by a whole lot...or just a tiny bit, when the table is shown from another angle. (00:02:25)
Other mistake: Commissioner Selwyn Patterson puts some pressure on Humphrey and the team saying that "a wealthy tourist has just been killed." But Dan Hagen was not a tourist; he lived on Saint Marie with his wife, as said by the fellow oceanographer Jonathan Taylor, and they have a villa. Someone as well connected and nosy as Patterson wouldn't miss the notion of a multimillionaire living on the island. He also says that he needs to reassure the yacht club that there are no pirates in the area, but it was already established by the coast guard that no ships approached the area. (00:12:15)
Other mistake: Florence closes her notepad and puts the cap back on the pen when Dwayne just begun telling everyone what the Gendarmerie reported about one of the suspects. She has no way to know by that point what Dwayne is about to disclose, and that Humphrey is about to leave with her. (00:17:05)
Answer: Most likely they had only tropical exotic drinks, he wanted an old fashioned English beer.