Mr. Browne juggles apples at the dinner table and drops one in the gravy, splashing his face and shirt collar. Later in the scene, his collar is spotless.

When Miss Price arrives on her motorcycle early in the film, the rider is clearly not Angela Lansbury until the close-up as she stops outside the post office.

The first time the kids are in the museum, Carrie's braids go from neat to messy and back several times.

When Miss Price, Mr. Browne and the children barge into the Bookman's room with the bed, the chain of his reading glasses is attached to the right side of his glasses. Seconds later, the chain has switched sides.

The machine gun crew abandons their weapons and runs. Five seconds later, the very same crew is set up in firing position.

Miss Price's house is minutes from the coast, and the White Cliffs of Dover are shown. Children wouldn't have been evacuated to that location. Children and many adults had already been evacuated from that area due to the risk of invasion.

The film starts with 'England in the August of 1940.' At the museum, the first woman taking evacuees says "anything to get these poor children away from those terrible bombings in London." The Battle of Britain was in full swing in August 1940, but London wasn't bombed until 7 September.

Miss Price reads the instructions for Substitutiary Locomotion, gets as far as "five mystic words. These words are:" turns the page, and discovers that the rest of the book is missing. The end of that sentence should've been printed on the other side of the page she was holding.

When the camera pans along the long line of museum pieces arraigned against the Germans, it show more arms and armor than exist in all the castles in Britain put together.

When marching at the beginning of the film, the soldiers of the Home Guard carry an assortment of old or makeshift weapons, like muskets, spades, and hunting rifles. Some carry army-issued Enfield .303 model rifles. At the time, the British government had specifically reserved all modern weapons for regular army use only, so the Home Guard wouldn't have had the Enfields.

British characters refer to "soccer" rather than "football." Both terms were used in Britain for most of the 20th Century. At one point, "soccer" was the preferred term in official printed materials there. For reasons that are not clear the term disappeared from common usage, nearly overnight, around 1980.

Charlie and Paul's haircuts are far too long. In the war years, boys' hair was much shorter. However, this is obviously not a mistake, because many children's haircuts were long regardless.

The closing shot of a British newspaper article includes the word "rumor" rather than "rumour."

When Miss Price is kicking her feet during the "Beautiful Briny Sea" number, one of her shoes comes off while she's kicking.

At the railway station, Mr. Browne is told that he must travel on the train which will carry milk from the country to London in the morning. Later, when Mr. Browne punches two German soldiers, they fall over empty milk cans on the platform.

When Mr. Browne referees the soccer game between the animals, he disappears from a few scenes before animals are shown.

The soccer ball transitions very jarringly from live action to animation.

When the market stall trader removes the necklace from around Carrie's neck, saying, "Who d'you think you are, the Queen of Sheba?", her mouth, reflected in the mirror, isn't moving.

When Miss Price attempts to ride her broom for the first time, the wires holding her broom up in the air are visible.

When Professor Browne's bewitched shoes dance by themselves, the string used to create the effect is clearly visible.

When Miss Price's nightgown floats out the door, the wires holding it up are visible.

After the armor on the horse is hit with the hand grenade and put back together, the wires holding the pieces up are visible.

Towards the end, when the star disappears from Mr. Browne's hankie, Miss Price said objects would not pass from one world to another. However they, the clothes, bed, and bedding passed from their world to Naboombu without issue.

The suit of armour that removes its leg, empties tens of bullets out, far more than was shot at it. In addition it has bullet holes in its back showing that the bullets went straight through and could not have collected inside.

Emilius Browne describes himself as the "late headmaster" of the Correspondence College of Witchcraft, which means he died. The correct term is "former headmaster."

Mr. Browne says he used to captain Tottenham Hotspurs. The football club is called Tottenham Hotspur (no s).

At the Portobello Road market, Miss Price checks all of the intact volumes on each stall to find the missing second half of Astoroth's book.

During the football match, when the ball is being hit up and down the pitch, Paul laughs while Carrie and Charles only just manage to keep straight faces.