Factual error: In the penultimate episode of series 2, the date is given as July 1973, but in an earlier episode when the police were raiding the drug dealer's house, Cozy Powell's record "Dance with the Devil" can be heard. This was a Christmas time hit in 1973.
Episode #2.8 - S2-E8
Factual error: The silver Ford Granada seen in the final episode is a Ghia model, which was not made until 1975.
Factual error: Sam's watch (which we see when he checks it just after the escape attempt) is a quartz movement "analog" with a little window at the bottom where an LCD (Liquid Crystal Display) display shows the date. LCD didn't appear on watches or calculators for another five or six years.(Although in 1973, there were Digital Watches with LED (Light Emitting Diode) displays. (You can see Roger Moore as James Bond wearing one in "Live and Let Die"(1973)).
Factual error: At the end of the episode Sam walks down an alley looking for the son of the murder victim. In the background small split-system air-con units are visible on the outside of some buildings. These were not available at this time. (00:48:30)
Factual error: There is a phone ringing in the police office, but it is using the American style ringing tone - with a single, repeated, long ring - instead of the British ring tone - two short rings repeated. (00:00:24 - 00:01:17)
Factual error: The reflection of a blue DAF XF lorry can be seen in a window. These lorries were not made until many years later. (00:31:51)
Episode #2.3 - S2-E3
Factual error: Sam and Gene arrive at a construction site to investigate stolen explosives. There is a green first generation Range Rover parked on the site. The Range Rover has its driver side (right side) side view mirror mounted on the door. In 1973 Range Rovers had side view mirrors mounted on the front end of the front wing (fender), not the door. The mirror was not mounted to the door until after 1978. (00:08:58)
Episode #2.6 - S2-E6
Factual error: In the back of the record shop amongst the audio equipment you can see 2 A&R Cambridge A60 amplifiers. These were not available until 1977.
Suggested correction: The show is set in a form of purgatory in 2006. It's not really set in 1973.
Factual error: Stopford House in Stockport is used for the exterior shots of the police station. It was constructed in 1975 and wouldn't have existed in 1973 when the show is set.
Factual error: Gay pride flags are visible in a window. The 6 color flags shown were introduced in 1979 (though an 8 color flag preceded it in 1978). (00:30:44)
Factual error: Throughout the show in many street scenes and visible on some houses are satellite dishes. These were not available in 1973, only terrestrial TV through regular aerials. The first commercial satellite service In the UK was launched in 1989 by SKY.
Factual error: The supposed keys used to kill Colin Clay were a modern type not yet produced at that time.
