Corrected entry: When Arthur Lowe, John Le Mesurier and Clive Dunn are walking across the street at the beginning of the movie, you can see the "Cats Eyes" in the centre of the road between each white line. These were not invented during World War 2.
Corrected entry: When John Le Mesurier calls for 5 rounds rapid fire from the van, towards enemy on the left, the soldiers deliver three "rounds", then when called upon to deliver 5 to the sky above, they deliver four.
Correction: The Warmington on Sea platoon is not an efficient military outfit. This could be a character mistake, rather than a film mistake.
Correction: "Cats Eyes" were invented in 1933 by Percy Shaw. In 1935, he opened a factory to manufacture them and a year later, the first 50 were laid in Bradford. They became popular throughout Britain in World War II. http://en.wikipedia.org/wiki/Cat's_eye_(road).
Dr Muppet