When Morse and Lewis get into the car the window is wound up showing a reflection of trees, bit in long shot the car window is fully wound down.
As an alibi one of the characters says he was working on The Flying Scotsman (a model of it on his railway) and trying to decide whether to take the train up the coastal route via West Hartlepool to Newcastle or stick with the inland route through Bishop Auckland. The inland route however does not go through Bishop Auckland, it (the main east coast line) goes via York through Darlington then to Durham to Newcastle. Bishop Auckland was/is simply a branch-line leading to the wear valley and east-gate quarry, Stanhope etc. and alternatively a branch-line also up to Barnard Castle, Brough etc but no line direct from Bishop Auckland to Newcastle that flying Scotsman could use.
Near the beginning Morse is facing the murder victim's wife when he tells her that her husband has been killed. She sits straight down. But in the next view she is sitting on a cushion at right angles to Morse. She would have had to twist around to land in that position. A bit tricky.
The radio announcer twice mispronounces the Oxford region of St. Aldates as St. Algates.