Carry on Behind (1975)

Revealing mistake: When the stripper appears from the changing room during the cabaret scene, the stripper music is heard, but if you look carefully the tape recorder which is supposed to be playing the music is not actually moving.

Prof. Anna Vrooshka: Tomorrow, we are poking holes all over caravan site.
Prof. Roland Crump: I don't think they would like that at all.
Prof. Anna Vrooshka: It's ok, we are poking early.

Trivia: In the butcher's shop scene at the beginning of the film, Fred rescues Ernie who has been locked in the freezer overnight. Jack Douglas was covered in frost effect plastic for the scene, but the rest of the cast/crew felt he had got away lightly, and threw him into a river.