When Sidney is changing the tire on the Mini the hub cap appears and disappears between shots.
When Sid Noggett (Anthony Booth) stops his Mini van outside the church at Timmy's wedding, he gets out and comes into the church. Behind him, the van starts to roll away backwards, but in the next shot is stationary. Either it was planned as part of the story that the van would roll away and the story was changed, or Booth forgot to set the handbrake when he stopped the vehicle.
Timmy's WPC girlfriend and the older WPC depicted both wear outdated uniforms. By 1974 their hats should have a white crown, not the black one depicted, with a Sillitoe tartan band (black and white check).