Visible crew/equipment: In "The Desparate Hours", right at the end when Barraclough is in Fletcher's cell, when Fletcher says, "I never heard nothing" you can see the shadow of the boom mic on his face.
There was an American version of this classic UK show. It was titled On the Rocks. The script was reworked in order to make the style of humour suit the audience. It lasted one series before being cancelled in May '76.