In wide shots of the colliery, showing the wheels of the winding engine, both wheels revolved in the same direction. This never happened with real collieries: one lift cage always rose to the surface as the other went down underground, in order to balance the load.
In the pub scene, when Gently and Bacchus are having pints together, behind Gently is a row of books. Some books can clearly be seen to be from the Readers Digest "World's Best Reading" Series, which were not published until the 1980s and 1990s.