When Gene is getting on the phone to Hyde, his cigarette is in his hand; when the shot pans to him on the phone, the cigarette is in his mouth and no time to change it.
When Sam is talking to Chris in the canteen, he mentions Heathrow Airport, which Chris seems not to recognize. London Airport was in fact renamed "Heathrow Airport" in 1966, seven years before.
But in 1973, the UK was a much more provincial country than it is now, and travelling abroad for holidays was only just starting to become fashionable. So it isn't surprising that a character from the north of England (who is also generally depicted as rather dimwitted) wouldn't be very knowledgeable about airports in the south of the country. It was almost certainly the intention of the scriptwriter to make this point in this particular scene.
But in 1973, the UK was a much more provincial country than it is now, and travelling abroad for holidays was only just starting to become fashionable. So it isn't surprising that a character from the north of England (who is also generally depicted as rather dimwitted) wouldn't be very knowledgeable about airports in the south of the country. It was almost certainly the intention of the scriptwriter to make this point in this particular scene.
The photo-fit picture of the Yorkshire Ripper on the police bulletin board wasn't issued until 1979.
While Sam and Gene are cowering on the back seat of the Toledo to avoid the gunshots Sam's slimline watch is clearly visible on his wrist showing a very futuristic LCD display at the bottom of the analogue face.