Factual error: As Bentley is shown round the control room of the plant there are modern LED light panels and modern health and safety stop buttons which would not have existed in the 1960s.
Character mistake: The registration number of Alan Salt's car is HUA222B, but when Rachel is on the phone asking an officer to look up the car's registered owner she gives the registration number as B222HUA.
Factual error: Gently and team shine a maglite torch into an underground chamber. The episode was set in 1970. Maglite torches weren't manufactured until 1979.
Factual error: The Daimler DS420 limousine seen in this episode has a C registration which dates it to 1965 these cars did not start production until 1968.
Factual error: Two cars in this episode set in 1964 are too new, Robert Stratton's Wolseley 1100 or 1300 is a mark two which didn't start production until 1967, and George Gently's Rover 3 litre is a 1966 mark 3 model fitted with rostyle wheels from the 1967 3.5 litre model.
Factual error: At the seaside the Bedford CF ice cream van is wrong on two counts - the CF was first produced in November 1969 and this van has a J registration dating to 1970-71. This episode was set in 1968.
Factual error: Episode starts "Durham 1966". When Inspector George Gently and Bacchus are questioning the girls on top of the "TV" studio the High Level Bridge is in the background and there are overhead electric masts on the bridge. Railways around Newcastle were not electrified until 1990. (00:22:00)
Factual error: John Bacchus is trying to sell his MGB sports car for £100, the car is less than a year old and would be worth much more than that - a new one would be about £850, and it wouldn't have lost 90% of its value in a year.
Factual error: When Gently and Bacchus pull up outside the house while looking for Hazel Joyce, Bacchus crosses the road to the sea front, the front end of a modern Vauxhall can be seen in the side road.
Gently Between the Lines - S6-E1
Factual error: Just before the end of the episode, the custody Sgt is arrested in connection with the death of the prisoner, and the modern day caution is used, which was not introduced until the '90's.