Blooper

Wendice throws a £100 bundle on a pink armchair. The money falls right at the back of the seat. A few minutes later, Swann takes the money which is now right in front of the armchair.

When Swann arrives and Tony pours two glasses of brandy, they both go and sit down and Tony does not bring the bottle with him. But later, as they are continuing their conversation, Swann refills his glass from a bottle and puts it down on the table.

When Swann is outside the apartment he checks his wristwatch and it shows the time is 10:53. The dial is plainly visible and has no brand logo. Once Swann has entered the apartment, he checks his watch again. The dial is visible and shows a time of 10:58. Partially hidden below the minute hand now is a miniature of a European steam locomotive.

After Tony removes the reunion photograph from the wall to show it to Swann, he re-hangs it tilted relative to the other pictures next to it. In the next shot Tony is returning to his chair and the picture has been straightened.

During the trial, the date of the murder is clearly stated as September 26th, but when looking at Tony's chequebook, Halliday says that March 26th was "the day before all this happened" and that Tony has been living on the cash in the briefcase "since the 27th of March".

When the scarf is burning in the fireplace after Wendice puts lighter fluid on it, he supposedly puts more on it, however, the fire doesn't change nor does it flash back, indicating that there was no fluid.

When Swann arrives at Wendice's flat, Wendice tells him they went to the same college but that Swann wouldn't recognize him because he (Wendice) had only arrived in Swann's last year. But immediately afterward Wendice takes the reunion dinner photo from his wall, showing Swann sitting right beside Wendice. Leaving aside the matter of why Swann and Wendice would be attending the same reunion since they had graduated years apart, Swann never contradicts Wendice's assertion that they hadn't seen one another in the 20 years since college.

This is because Swann doesn't recognize him from the reunion dinner which, incidentally, does not mean they graduated in the same year, it could be an alumnus dinner for anyone who graduated from the same university.

During the montage of the trial, Margot shakes her head no to the various incriminating questions; in a real trial she would have been required to answer verbally.

This is obviously not meant to depict a real trial, it is a classic piece of Hitchcock stylization to indicate Margot's state of confusion and distress at being tried for premeditated murder.

When Tony and Mark are getting ready to go out, Tony pulls the curtains behind the desk closed after looking outside for a second or two. He asks Margot to borrow her key and Mark says he will go out to get them a cab. Tony steps behind the desk and pulls the now open curtains closed again. He also takes another short look outside.

There are two sets of curtains and two sets of doors and Tony closes them separately.

After the Inspector switches raincoats without Tony's knowledge, as Tony leaves his apartment, he pulled the door shut causing the door latch to lock the door without the need of a key from the outside.

When the Inspector enters the apartment, he tosses his hat onto the standing umbrellas by the door. He never retrieves his hat when he leaves later. However, the Inspector actually moves his hat several times, including picking it up from its original place on the umbrella stand.

Margot's press cuttings are clearly blank on one side; cut out of newspapers, they should have printing on both sides.

The photograph of the college class reunion has obviously been doctored. It is obvious that the heads of Ray Milland, Anthony Dawson, and Alfred Hitchcock have simply been "cut and pasted" onto the bodies of three other men in the original photograph.

When Inspector Hubbard is looking out the bedroom window at Margot and the policemen walking toward the apartment, their legs suddenly disappear from view, revealing where the projected scene of the street meets the edge of the physical set. Close inspection of faces suggests that a double was used for Grace Kelly in the rear projection. When Margot enters the apartment from the street, the background is an obvious still as the two policemen and pedestrians are motionless.

As Wendice walks out the front door after trying unsuccessfully to get into his flat, Hubbard describes to Margot and Mark what he's doing. Wendice at first gives up on why his key doesn't work and is shown turning away from the entrance and starting to walk off. The camera then cuts to Hubbard, who says, "It's no good, he's going away down the street." But then Hubbard says "Oh, just a minute", and as the camera cuts back to Wendice, he's barely moved. Given the time that has elapsed while Hubbard was speaking, Wendice should be several feet away.

When Tony dials the first phone call in the movie, it's clear from the sound and his finger movements that the fourth digit is smaller than the third, perhaps a 4. But from the immediately following dialogue, the number should be HAMpstead 7899, i.e. 426-7899.

In a shot of the Queen Mary, a part of the wall holding the backdrop is visible.

When Chief Inspector Hubbard uses his penlight to illuminate the telephone dial (and later to show the lock on the apartment door) the area of light is shaped and moves like an off-screen spotlight (which it is).

When Tony phones the police from the flat, supposedly in London, we hear a clearly American-accented voice on the other end say "Operator". It should have been an English voice, saying (in the 1950s) "Number, please."

After the trial, Chief Inspector Hubbard visits Tony to execute a complicated ruse that he had prearranged with Sergeant O'Brian (at the station) and Detective Williams (stationed upstairs). The ruse relies on Hubbard mentioning Margot's handbag and switching raincoats with Tony. Hubbard would have left the flat without doing either of those things had it not been for Mark being present and calling out to Hubbard, but Hubbard would not have expected Mark to be in the flat.

After Tony returns to the flat after the botched attempt on Margot's life resulting in Swann's death, he finds a stocking outside the patio doors. There would be no stocking outside, since Swann was always indoors.

The boom mic is reflected in garden doors above Tony's and Inspector Hubbard's heads during the Inspector's first visit.

Chief Inspector Hubbard forgets to show either Tony or Margot his ID when he visits them at their flat for the first time.