Continuity mistake: In the episode "The Wedding Party", the first two rooms on the second floor right of the stairs were 11 and 12. Yet in this episode, those two exact same rooms are now 5 and 6. (00:19:20)
Continuity mistake: In this episode, Basil hides in a closet to try and trap a girl staying the night in a guest's room. However, in other episodes ("Wedding Guests," "Communication Problems," and "The Kipper and the Corpse"), there is a room in the same spot the closet is in this episode.
Continuity mistake: After the woman screams, Sybil knocks the wall and you can see it move.
Answer: It's "Leisure Complex" by Dave Gold and Gordon Rees. Can be found on YouTube. The relevant clip is around 25 seconds in.