There is some talk of the turnscrew being "case hardened", according to Lovejoy a result of being shut up in the pistol's wooden case for centuries. In actuality, case-hardening is a process by which additional carbon is baked into the outer surface of a steel part to increase surface hardness while maintaining a less brittle core.
The credits list Anthony Dutton's character as "Supt Blythe"; however, when he introduces himself to Lovejoy, he gives his rank and name as "D/Supt Parris"