As the characters drive around London, there are no indications of any of the precautions taken to reduce damage during air raids - sandbags at doorways to deflect/ absorb blasts, tape on windows to prevent glass being blown into houses.
In the first minute or so there's a shot of the nearside front wing, bonnet and bonnet mounted spare wheel on a 4x4 type vehicle. This is a Land Rover which wasn't developed until several years after the war had ended.
There is no attempt at 'compartmentalisation' of the agency. Normally personnel working in such an organisation would only be allowed to interact with other personnel relevant to their role. This limits the chances of penetration by a spy.
When Captain Ransome collects the newly arrived female agent Rolande from his flat, they leave the courtyard outside in a car which passes a 1950's Vauxhall Wyvern with a tarpaulin draped over the back to camouflage it.
Ranson, as an intelligence officer, should have known better than to become emotionally involved with an operative.
Rolande would not have had direct contact with other enemy operatives, as this would have placed them at risk of exposure. Contact would have been by clandestine means.