Almost all windows during the war were taped with what looks similar to masking tape to minimize flying glass in the event of bombing. This was not evident anywhere in the film, even in scenes in Southampton (which is even shown being bombed early in the film).
Many vehicles shown in the film did not have "hoods" over their headlights, which were required by law during the blackout to prevent light sources becoming navigational beacons for enemy aircraft.
When Stella receives a phone call from her fiancé, she tells him that the "pips" are going and that he should insert more money to continue the call. The "pips" did not come in until 1959. Prior to that local calls were unlimited in duration and long distance calls were via the operator, who would announce when your time was up and you needed to insert further coins.
In the shot of the train approaching the farmer's son standing on the line, a British Railways insignia is visible on one of the coaches. This was not used until the railways were nationalised in 1948.
When the land girls watch the bombing of Southampton from several miles away, the flashes and sounds of the explosions are simultaneous. In reality, due to differences of speed, the sounds would arrive approximately 5 seconds later for every mile of separation.