The One In Barbados, part 1 - S9-E23
Revealing mistake: On a number of occasions in this and the next episode, the beach and the water can be seen in the background, through hotel windows. White foam is visible in a number of places, like the crests of waves, but not only do they not move while the camera is on them, they are always in the same place in subsequent shots, revealing that this is a painted backdrop. (00:26:40)