When the townsfolk row out to the ship 'The Cabinet Minister' after it's been abandoned on the rocks, all the ship's lights remain on even though the engines that would power them are not running.
Historically inaccurate vehicle. The motorcycle and sidecar combination used in the film clearly has telescopic front forks, these didn't become common until well after WWII - the bike used was a 1954 BSA model M21.
When Sgt Odd opens the Post Office door and sees Captain Wagget standing there they both stand to attention and salute each other. This is incorrect. In the British armed forces you do not salute if you are not wearing head wear, instead you you only stand to attention.
When Waggart leaves Odd on the quayside, Waggart salutes first which is wrong, the junior rank always first.
When Dolly says her mother said "Dolly, never trust a native", Captain Wagget replies "Yes, but that was in Ranchipur during the Raj", suggesting that the Raj was in the past.
The Raj didn't end until after the Second World War, in 1947.
When Brown is talking to Mrs Wagget he refers to the Ministry of Defence. This wasn't established until 1964; during the war the Army was administered by the War Office.
When the Doctor is stopped in his Alvis it is showing an Alvis Owners Club badge on the front bumper. The AOC wasn't formed until 1951.
The description by the school girl correctly places the location of Toddy in the Outer Hebrides west of Scotland. However at the barricade scene, Captain Wagget's reference to Norway being just over there would put Toddy on the east side of Scotland. Also the reference to the Skerrydoo, puts Toddy in Ireland.