Goofs

During the parrot chase scene, Mr. Lawson is seen to fall over breaking the chair he is stuck in. Immediately after Mr. Harvey breaks the gramophone record the same shot is reused and Mr. Lawson apparently falls over breaking the same chair for a second time.

When Mr. Robinson approaches the house during the tea party it is dusk, the street lights are on and a car is parked with its lights on. In the next cut the lights are off and the car has disappeared.

The framed photo which Alec Guinness adjusts has moved slightly from the previous scene when he first sees it.

On the night of the first music practice when the Major arrives at Mrs. Wilberforce's, the sky is twilight behind him. Then Mr. Lawson and Mr. Robinson arrive and the sky is almost pitch-black. Then Louis arrives and it's twilight again.

One-Round knocks down a door, but after the gang pick matches the door is back in its frame.

The gramophone record Louis (Mr. Harvey) breaks is Hoffstetter's String Quartet in F Major, Op.3 No.5 'Andante Cantabile', which is not heard again in the film. It is not Luigi Boccherini's String Quintet in E, Op.13 No.5.

Some viewers have noted that the card placed in the shop window advertising the rooms to let states "Apply within or to Mrs. Alexandra Wilberforce" and yet when Mrs. Wilberforce's friends arrive at her house they all refer to her as "Louisa". However, it's possible that "Louisa" may be Mrs. Wilberforce's preferred middle name or nickname.

When all the money falls out of Lawson's cello case it scatters all over Mrs. Wilberforce's doorstep. By the time the criminals come back to try and cover up the story, all the money has disappeared. However, the gang had already picked the money back up off-screen.

The parrot Mrs. Wilberforce clutches after it is rescued is clearly stuffed.

At the end of the film, when Mrs. Wilberforce is back in the police station and talking to the officers, the constable behind, and to the right of her is not wearing his whistle and chain on his tunic (unlike the superintendent). This would simply not have passed muster in the days that the film was made.

When the gang pile into the phone box after the robbery, if you look carefully you can see the right side of the booth briefly flex indicating that this is a wooden prop. British phone boxes of the time were made of metal so would not flex in such a manner.

When the gang block the van during the hold-up and one of the guards puts his head out of the window to remonstrate with them, what he says is out of synch with the movements of his mouth.

When Major Courtney is cornered on the roof by Louis, he backs away and shouts, "Louis!" but his lips do not move.

From the street in front of Mrs. Wilberforce's house, the front of St. Pancras station is visible, placing the house south of the station. No tracks leave St. Pancras or the adjacent King's Cross station in that direction, so the house could not be adjacent to a tunnel as depicted (see trivia entry).

When the group first arrives at Mrs Wilberforce's, they go upstairs and - if the gramophone is to be believed - immediately begin playing. However there are no sounds of any of the players tuning their instruments first, which should have given away the fakery.

When the policeman calls at Mrs. Wilberforce's house, he introduces himself as "Sergeant McDonald". At the end of the film, the Inspector refers to the same character as "Sergeant Harris". In the credits he is simply listed as "Sergeant".