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: 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)
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)
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)
Answer: Most likely they had only tropical exotic drinks, he wanted an old fashioned English beer.