Patzer

When Thornhill is writing the message on the matchbook, the message takes up three lines and reads "They're onto / you - I'm in / your room." When Eve opens the matchbook below, the message takes up four lines and reads "They're on to / you / I'm in your / room." The matches also change from being half full to totally full.

Thornhill is taken from Mount Rushmore in an ambulance with a hatchback-style rear gate, which is the correct rear door for an ambulance conversion of a station wagon. When he arrives in the forest to meet Eve, he emerges from a station wagon with a standard lower tailgate and upper hatch - not an ambulance.

At the very beginning of the film, Thornhill is seen walking down a crowded New York City sidewalk. Some of the people walking in front of him also appear walking behind him.

Thornhill complains that he only has one suit for his stay in Chicago, yet when he heads out into the prairie he has a different colored suit on. Director Alfred Hitchcock claimed that it was actually the same suit that just looked a different color due to film color-matching techniques. However, according to Eva Marie Saint, Cary Grant loved clothes and didn't want to see the blue suit from the hotel scene in Chicago trashed from crawling round in the dirt to avoid the crop duster. So, a different suit was used for that scene (which happened to be a different color).

In George Kaplan's room at the Plaza Hotel, we see a close-up shot of Thornhill pressing the call button for the maid. Visible in this shot is a telephone with a coiled cord. But in all other shots that show that phone, it has a straight, non-coiled cord.

When the Mercedes carrying Roger is balanced on the rocky cliff, the left rear wheel is spinning in the air. Moments later, the car drives back on to the road. In a rear wheel drive car from the 1950s, all of the torque would be delivered to the free wheel, making it impossible for the car to move without being pushed or pulled.

When the crop duster is assailing Thornhill, the bullets hit the ground after the plane has passed. In strafing, even more so in a slow-flying biplane, the bullets would arrive at the target well before the plane passed.

In the crop dusting sequence which allegedly takes place in northern Indiana the highway 41 sign is square which is incorrect. Highway 41 is in fact a U.S. highway which has a completely different shaped sign. Only the secondary state highways have square signs.

When Roger Thornhill leaves Chicago for that rendezvous with the machine-gunning crop-duster, he is shown standing on a Highway 41; which would be the correct number. However, it is designated on the highway sign as "Indiana Route 41". In reality Route 41 is a U.S. Highway Route and is identified so with the white shield emblem with black letters.

During Roger's drunken car ride his left rear wheel swings out over the cliff for a few moments before the car manages to pull itself back onto the road. This would be impossible. The weight of an automobile is too great to allow this to happen. The left rear quarter would sink instantly and drag the rest of the car over the cliff with it.

The line "our friend who's assembling the General Assembly" is a deliberate play on words, and it's in the script. It is not a case of Thornhill (or actor Cary Grant) erroneously saying "assembling" instead of "addressing".

Someone who resembles Thornhill gets off the train without a suitcase; it's possible to confuse that person with Thornhill, who has a suitcase under his arm.

In the jailhouse, Thornhill is taken to a doctor for a sobriety check; one of the cops draws a straight line with chalk onto the floor. This is to test if Thornhill can walk a straight line. However, the doctor declared him intoxicated without ever conducting the line test.

Roger immediately admits to the doctor that he is "gassed" so there is no need to perform the line test.

On the train between New York and Chicago, Eve Kendall says she is unmarried and that is shown by there being no wedding ring on her finger. Later on in the hotel room in Chicago, Eve is shown wearing a ruby ring on the ring finger of her left hand.

A ruby ring is not the same thing as a wedding band regardless of what finger it is being worn upon.

During the scene in the diner at Mount Rushmore, a boy in the background anticipates the surprise gun shot fired by Eve by putting his fingers in his ears.

When Roger leaves the train in Chicago, the Redcap uniform he is wearing is a perfect fit. Yet, when you see the man from whom he got the uniform, he is a very short little man whose clothes would never fit Roger.

Every indication is given throughout the film that the action takes place in the summer. The trees in New York City are in full flower, ditto the foliage at the Long Island estate, the Indiana cornfield landscape is scorched, the way people are dressed, especially in the Chicago as well as South Dakota scenes, yet the newspaper which the Professor and his colleagues read recounting the murder of Lester Townsend carries a late November date.

The film was actually shot from mid - late August through September, 1958.

When the professor stands by a window, the entire background showing the Capitol building shakes for a brief moment, making it obvious that it is not real.

In the Chicago police car after Thornhill's arrest at the auction house, the cop on Thornhill's right forgets to lean as they simulate a turn. Cary Grant can be seen giving the errant actor a poke in the arm.

There is no way the sergeant could have fatally shot Leonard ( Martin Landau ) from an estimated 200 yards with a revolver. the hand held shot even with a scoped rifle is questionable.

When the professor brings clothes to Thornhill, who is confined to the hospital room for a few days, Thornhill starts to get fully dressed immediately. The professor sees Thornhill starting to get dressed but does not question why he's doing so since he's confined to the hospital room, in bed. Thornhill does, in fact. escape, clothed, out of the window after the professor leaves the room.

When Cary Grant's and Eva Marie Saint's characters arrive at Grand Central Terminal, they hear the P.A. announcer call a couple of times for their train, the Chicago-bound 20th Century Limited, train number 25. On board the train, however, Eve says her bedroom is in car 3901. NYC's train number 39 was the North Shore Limited, which left New York shortly after noon.

Eve's line "I never make love on an empty stomach" is overdubbed with "I never discuss love on an empty stomach".

The airstrip at Vandamm's place clearly seems to be a gravel strip. Yet, as the plane touches down, a brief tire screech is heard, as from a plane setting down on a concrete or asphalt strip.

At the end, when Thornhill is pulling Eve up onto Mount Rushmore, he says to her "Come along, Mrs. Thornhill," but his lip movements don't match what he's saying.

When Eve and Roger are kissing after the porter leaves the compartment there is no movement nor is there any noise from the train. You can even hear Eve leaning against the wall of the compartment as it creaks as Roger presses against her.

When Thornhill escapes from the Mount Rushmore house and runs over to the black Ford, he is shown opening the car door and just starting to get in while on the soundtrack the sounds of the door being closed and the ignition being turned on are heard.

When Thornhill and his mother are changing elevators you can see a crew member bend over in the reflection on a pane of glass.

As the plane crashes into the truck, wires are visible on the right-hand side of the screen.

During the climactic Mount Rushmore scene at the end of the film, the top of the mountain set, and equipment, are clearly visible for a number of seconds.

There are a couple of shots looking out over the tops of the monument's heads. In one of them, two presidents face the other two. The actual monument has three presidents facing one.

As the drunken Roger is placed in the car by the kidnappers, waves can clearly be seen crashing into a rocky coast line with a large drop to the sea. The scene takes place in Glen Cove, New York, as evidenced by the police car, but there is nowhere on Long Island that has a coastline like this.

In the LaSalle Street Station scene in Chicago, the announcer calls the departure for the "New York Special" as 10:00 A.M. Central Daylight Time; however, the newspaper the Professor reads earlier in the movie dates the action to November, when Chicago would have been under Central Standard Time.

As Roger Thornhill returns to the Ambassador East in Chicago after the traumatic scene in the cornfield, you can see a palm tree near the hotel. There are no palm trees in Chicago or anywhere in the Midwest.

When Thornhill and Kendall are being pursued on top of Mt Rushmore, there is a scene where you can see the sculpted heads of Theodore Roosevelt and Abraham Lincoln facing the same general direction. In fact, on the real structure, Roosevelt's sculpture is recessed behind the other three presidents and facing towards Lincoln.

Initially, when the plane attacks Thornhill it flies low in order to hit him. Following that it tries to machine gun him down. It then goes back to the flying low tactic. A plane can't fly low enough to run a person down as if it was a car. It would mean a certain disaster for the plane. Also, the logical option is to use the machine gun but it ceases firing and goes back to the flying low tactic. The aforementioned makes no sense.

At the Chicago station when Eva tells Thornhill to take a bus to meet Kaplan, in the long shot with the column behind them, the boom mic is clearly visible wobbling above.

During the auction, someone bids $2000 for an item and the auctioneer says, "I have 2000." A short time later, the auctioneer says, "I have 2250" and the item ends up being sold for that amount, even though nobody has bid more than $2000 for it.

At the beginning when Thornhill grabs the cab, the secretary enters first but she doesn't scoot over and remains behind the driver. He then climbs over her and sits behind the front passenger's seat. This is not normal behavior. However, later on, when Thornhill gets dropped off, it becomes evident why they did this. Thornhill exists directly onto the sidewalk, then there's a medium shot of him as the cab pulls away; thus, it was done for the camera setup.