Character mistake: Florence grabs the victim's phone with a tissue to avoid leaving prints...but then uses her other bare hand to go through her messages via touchscreen. In many other scenes she's just seen wearing latex gloves. (00:12:30)
Continuity mistake: Dwayne's bushy cover has been blown, so he nonchalantly walks out and greets the stern-looking Audrey. He opens his arms when he says her name, but in the reverse shot he repeats the movement, as he was still pretending to scribble on his pad. (00:14:00)
Character mistake: A computer display of currency transactions shows the word "withdrawal" spelled as "withdrawl." (It is also spelled correctly higher up on the display). (00:25:05)
Character mistake: The forensics report in its first screen displays the word "antybodies", when of course it is "antibodies" (00:25:15)
Continuity mistake: DI Jack Mooney is looking at the coroner report on the PC screen. He changes his stance and is initially hunched over and then straight, but the person in the foreground is keeping the exact same posture every time the camera cuts to Dwayne. (00:25:35)
Continuity mistake: After the obligatory ultimatum visit by the Commissioner, Jack asks Florence for good news. When she chirps that she -really - found something, her hands drop in the close-up, but are holding the headphones steady and up in the next shot. (00:32:25)
Continuity mistake: After the chat with the hotel manager, Jack and Florence are in Stephen's room. The level of drink in Stephen Marston's cocktail glass changes between shots - it's half full when Jack is straining to sit down, and is back up right at the cut. (00:35:25)
Other mistake: The text message used as ploy to cover up the murder was sent at 17:44, but during the flashback showing the killer setting up the murder scene, a wristwatch on the vanity is at about 10 o'clock. (00:44:25)
Plot hole: The murder as described makes kinda sense (it's a device used in other works of fiction), but not at all as shown; the person hiding in the bathroom closes the door to the point of making it click, and opens it also with a click. Even panicked, the other person in the room is going to hear the sound of a lock right behind him. The door should have been closed only partially. Moreover, the bathroom door is right by the front door closed just by the door chain, and Philip Marston had the door unlocked and with just the chain to break; the bathroom door was fully in his view the whole time.
Character mistake: Dwayne tells Jack on the crime scene that the victim (who had two aces, with one ace on the board) he had "three of a kind or as the pros say, trips." Pros don't say "trips" to that though, since "trips" happens when two cards matching one you have in hand are on the table. Holding the pair makes it a "set." (00:06:25)
Other mistake: Meeting with the suspects for the first time, Jack is flipping through the brochure with the player profiles while "The prof" is saying that logistically speaking the murder is impossible. Jack looks down at a page, but the close-up shows a different one. (00:08:35)
Continuity mistake: Officer Dwayne Myers pulls the shades from the sock; he is holding them in a different way between shot and reverse (fingers on the lens vs fingers on the hinge). (00:12:00)
Continuity mistake: Office scene with the poison being revealed. Dwayne in his snazzy detective suit interjects that you have to know the right, or wrong people to get a hold of it. In the wider shot (whole room in frame) Danny John-Jules' left hand covers the cuff of his blue shirt, while in the closer angle the shirt is perfectly visible. (00:13:50)
Continuity mistake: After mentioning the Dutch poker player, JP waves around the calling card of the taxi driver. He holds it vertically when seen from behind, horizontally in the front shot. (00:27:50)
Continuity mistake: During the questioning of "professor" Eugene Sutton, his hand is flat on the table in front views, with the side down in the reverse angle. (00:34:00)
Continuity mistake: During the denouement, the natural light on the poker table changes continuously between shots. (00:41:45)
Plot hole: There is simply no way that the cheating presented in the episode, with the player reaching in his pocket to mark the cards, consistently for over 5 years (!), and wearing the same obvious prop, could go unnoticed, especially in official tournaments with millionaire prizes, on camera even.
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: 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: 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)
Answer: Most likely they had only tropical exotic drinks, he wanted an old fashioned English beer.