Some Mothers do 'Ave 'Em (1973)

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.

Learning to Fly - S3-E7

Frank: I didn't know what a girl was until I was twelve years old.
Betty: You must of done.
Frank: How could I. I'd never seen one.

eric 64

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.