The Wedding Party (a.k.a. Sex) - S1-E3
Revealing mistake: Basil goes back to the second floor chasing after Polly. As he passes the last part of the banister, he touches the edge of it and it wobbles like rubber. (00:24:00)

Starring: John Cleese, Connie Booth, Andrew Sachs, Prunella Scales
Genres: Comedy
The Wedding Party (a.k.a. Sex) - S1-E3
Revealing mistake: Basil goes back to the second floor chasing after Polly. As he passes the last part of the banister, he touches the edge of it and it wobbles like rubber. (00:24:00)
The Builders - S1-E2
Deliberate mistake: When Basil is arguing with Polly and eventually decides to call O'Reilly, he trips over the gnome. However when we see Basil come out from behind the desk, he takes the gnome out of a side gap in the desk, perfectly out of reach of Basil tripping over it. (00:14:30)
Question: When Polly is laying in bed disguised as Mrs Fawlty, was that really Prunella scales playing that part? I was wondering as Polly as a more thinner face than Sybil and could never have really got away with it.
Chosen answer: Indeed it is Polly. She has stuffings in her mouth to pretend she is swollen.
Mortug