The teacher has her price tags on her shoes in the final scene.
At Kings Cross station, MkI carriages are clearly seen. These weren't introduced to the UK railway network until 1951.
If Eel Marsh Island is located in Essex, as discussed in the first film, why did the school party depart from King's Cross Station?..
In the final scenes miss Perkins is driving the Jeep under pouring rain, and is still raining hard when she runs trough the garden before the house -which is quite overgrown- yet her coat is perfectly dry once she steps inside the house.
In the last scene whilst leaving the house, there is a modern Yale lock on the door.
In the last shot of Miss Parkins and the boy walking down the street, one of the paving slabs has a small black strip in the middle with the letters "CATV" written on it. Cable television was not available in the late 1940s.
Once Harry has dragged Eve and Edward up from the depths of the marsh, and they are recovering on the foreshore, Eve's dress and Edward's shirt are perfectly dry.
In the blackout in the cellar, why don't they switch on the pilot's torch whilst trying to light the candles?