The car which goes off the road and is wrecked during the chase sequence is about one decade more recent than the one in which the principals have been driving, and from which they emerge after the wreck.
When arming the bomb prop, Nayland Smith first plugs in some wires before pretending to turn a black dial, which clearly doesn't move.
As the two soldiers stop for a cup of tea, one leans his rifle against the table behind them. It then slowly falls over, totally ignored by the two men as they discuss the weather.
Sir Charles claims that Gaskell lives in a barn in Essex, "no electric lights, no telephone." Later, Petrie claims that he has Gaskell's Essex address from Sir Charles's secretary, "and his telephone's been cut off."