Factual error: Jack listens to an interview with the fictitious novelist Frank O'Toole who appeared on BBC 4's Radio Island Discs. The episode is labeled "Fri 9 Nov 1989", but November the 9th in 1989 was a Thursday, not a Friday. (00:16:00)
Continuity mistake: When Jack realises the obvious and waves the calling card around, he's holding it in a different way between shots, with the thumb in the upper corner as he shouts "I know who Otis Falconer is." (00:41:25)
Continuity mistake: After the chat with Gilly White taking out of the trash, Jack picks a bottle to show it to Florence; he holds the bottle by upper or lower part of its neck, depending on the camera angle. (00:12:20)
Continuity mistake: When Florence reads the morning note left by the victim, in close-up she's holding it in a different way than in the following view; from one hand it goes to both hands, and the Bic pen in the second shot passes between index and middle, not the case in close-up. (00:06:35)
Continuity mistake: On the beach after identifying the murder weapon as a knife, Jack walks off and says that there are 1,000 ways to kill a man. Officer Dwayne Myers is holding the camera at belt level and with both hands, but in the next close-up on Ardal O'Hanlon he's in the background with the arm down his side, the camera reaching the knee. (00:06:00)
Continuity mistake: In the first part of the denouement, DI Jack Mooney is waving the victim's book around holding it in one hand when shot from the front, both hands from the back. (00:42:25)
Continuity mistake: During the toast, Gilly White staggers for a moment. As different camera angles alternate, she is holding the champagne glass either sticking a finger out or not. (00:01:45)
Continuity mistake: The victim's agent, Larry South, is holding Jack's calling card with one hand in close-up, both in the immediate follow-up. (00:09:20)
Plot hole: The author uses a typewriter and avoids technology. His fake identity was built on a laptop kept on another island. But in the big reveal, her guilt is predicated on her having seen the laptop to find out he was leaving her.
Answer: Most likely they had only tropical exotic drinks, he wanted an old fashioned English beer.