Continuity mistake: When Goodman jumps up yelling "yee-haaw!" messing the wedding table, Commissioner Patterson grabs a towel with his left, but at the cut he is using the right hand to clean his left. Likewise, Florence has in the second shot a hand on her chest, but she didn't have that pose already in the previous, it was just her initial reaction. (00:38:00)
Continuity mistake: When Goodman sprints away from the banquet, the cue cards in Dwayne's hand move from both hands to a lowered left hand in the faraway shot. (00:38:40)
Continuity mistake: DI Goodman is inspecting the pillows; when he gets to the second bunk bed, you can see that handling the pillow he accidentally catches with his arm a blue piece of clothing placed on the railing, dragging it a little along the way, towards the vertical support bar. The next shot is evidently from a previous take, because that blue rag is in the initial position, away from the bar. (00:39:10)
Continuity mistake: Humphrey gets next to Leo's bed saying "Hey sexy." He has a hand in his pants and the other on the phone, but they swap place at the first cut. When he gets up and protests that he loved Sian, the phone disappears. (00:39:10)
Plot hole: Why would Sian let Griff into the shower room if she broke up with him the night before?
Factual error: The stratagem used to conceal the murder and disguise it as suicide is absurd from the start; it relies on the old trope of a gun "silenced" shooting through a pillow. It simply does not work, a gunshot in the early morning in the empty camp would have not been dulled down significantly by a pillow, and still be heard.
Plot hole: The shower room door has a lock, that as shown in the denouement the killer never closed - making it fairly obvious that the victim did not lock herself inside the room to kill herself. Another minor but still significant problem with the stratagem used; the killer shot the girl in the chest; even if they didn't do any gunshot residual test on her hand, the trajectory of the bullet still would have proven the impossibility of a suicide.
Answer: Most likely they had only tropical exotic drinks, he wanted an old fashioned English beer.