As Sir John interviews Mary in jail, it is established in long-shot that both are sitting at opposite ends of a long table. During frontal closeups, the widths of the planks that make up the tabletop reveal that very randomly either the table is turning between shots or both persons repeatedly switch places.
The exact same continuity error also applies to the American version of the movie, Murder! (1930).
The exact same continuity error also applies to the American version of the movie, Murder! (1930).