Fred Carter walks down the path of his home, steps on a roller skate, and falls. He holds his left leg and says he has broken it. He is then helped back into the house, hopping on his left foot and holding his right leg up.
At the beginning of the film, when Sir Giles phones Jack Hopkins' cottage and Nellie Carter says that he has just left, the traction engine is initially seen with its left wheels parked on the verge on the same side of the road as the cottage. In a reverse-angle shot from the cottage, as Nellie watches him set off, the traction engine is now parked with its right wheels on the verge on the opposite side of the road.
As Jack Hopkins tries to fix The Duchess of Avon traction engine, rain visibly falls behind him, but in the very next shot with Kathy at the top of the Ferris wheel the rain had not started, although it does within seconds.
When Jack Hopkins and Paul Fisher drive the Iron Maiden into the road pit trap dug by the admiral, the front wheels of the tractor are in the pit. When they go to dig the tractor out, the front wheels are on the road and the large rear wheels are in the pit.
When Paul Fisher chops down the wooden signs with an axe to create firewood for The Iron Maiden, a metallic clang (instead of a dull thump of axe on wood) is dubbed on each time the axe strikes the sign.
The plane is supposed to be a civilian airliner but what's seen is a Victor Bomber.