Wendy House - S3-E2
Other mistake: When Frank, Betty and the insurance assessor are sitting on the sofa, it's obvious that all three actors are trying hard not to laugh when the assessor starts sinking into the sofa.
Some Mothers do 'Ave 'Em (1973)
1 other mistake in season 3
Starring: Michael Crawford, Jane Hylton, Michele Dotrice, Jessica Forte
Genres: Comedy
Moving House - S3-E1
Revealing mistake: At the beginning when Frank is directing the vans, we see that one gets its windscreen broken by a ladder from another van. However, the glass breaks just before the ladder touches it.
Frank: My father was in the battle of Britain, he was shot down seven times. I wanna be just like him.
Trivia: Michael Crawford was the producers' third choice for the role of Frank Spencer. The part had been previously turned down by both Norman Wisdom and Ronnie Barker.