Both times the main characters drive to the old mission, the wide shots show them driving on the right side of the road. However, all shots inside the car show them driving on the left side of the road. This is because the US 101 - where filming took place - near San Juan Bautista is split, with two lanes in each direction, by a grove of Eucalyptus trees. The film shows only one of the road's directions, giving the appearance that Scottie and Madeleine are driving on the wrong side of the road.
During the opening scene when Scottie hangs onto the rain gutter, the tiling of the roof top he slid down changes from flat wooden tiling to half-cylindrical brick tiling when the police officer returns to try save Scottie. Close-up shots of the police officer show half-cylindrical brick tiling, whilst the medium shots with the officer and Scottie hanging on, show flat wooden tiling.
When Madeleine is in Scottie's apartment after he rescued her from the bay, he offers her two cushions to sit on in front of the fireplace. When he picks up the cushions, they are green. In the next shot, when the cushions are shown hitting the floor, they are gold. When the cushions are shown lying in front of the fireplace after Madeleine has fled, they are green again.
When Scottie takes Madeleine out of the water, her shoe is off. When they have reached the pier, Madeleine has both shoes again.
As Scottie turns into the flower shop alley, the wall to his right has no windows. When he exits his car, windows have appeared.
When Scottie follows Madeleine driving through various San Francisco streets, he makes several turns onto intersecting streets, but he only rotates his steering wheel slightly each time. Steering wheels in the 1940s, and 1950s, and even most of the 1960s, required a full 360 degree rotation to make a right angle turn.
When Scottie is following Madeleine, whilst they are driving, they both turn left in their cars past a No Left Turn sign in the intersection.
Scottie doesn't suffer from vertigo (caused by an inner ear infection). He suffers from acrophobia (a pathological fear of heights).
Detectives in San Francisco are not called detectives, but are referred to by their rank, such as Sergeant and (more often) Inspector.
Carlotta, Madeleine's great-grandmother, was born in 1831 and died in 1857 as indicated on her gravestone. This would place her grandmother's birth at around 1850, her mother's birth at around 1870, and Madeleine's birth around 1890. This would then make her around 68 years old when the story takes place, instead of the 25 or 26 that she is supposed to be.
When Madeleine arrives at Scottie's apartment to post a letter, the establishing shot shows only a few bushes by the metal railings. However, in the closer two shots, more bushes can be seen against the railings.
When Scottie is following Madeline, whilst they are driving, Scottie's car turns a couple of seconds before his hand turns the steering-wheel.
When Scottie buys new clothes for Judy at Ransohoff's, Judy is shown trying on a pair of shoes. Due to the extremely low camera angle when Judy walks away from the camera, it's easy to see that the shoes are not new- their soles are heavily scuffed.
When Scottie gives Madeleine a cup of coffee in his apartment, the high camera angle shows that the cup is empty.
When Scottie and Madeleine are driving on a forested highway, the car appears to be on the wrong (left) side of the road.
When the manager of the McKittrick Hotel first appears, she says, "Yes?" to Scottie off screen; a moment later, her mouth forms the word without any sound.
As the camera moves away from Scottie standing at the edge of the tower, the shadow of the camera can be seen for a split second on the outer wall of the tower. On the Alfred Hitchcock Masterpiece Collection DVD, the image is cropped so the shadow cannot be seen.
A hand mysteriously rises from behind a gate over James Stewart's left shoulder (as he follows Kim Novak) and waves at the camera, about 55 seconds into the Mission Delores graveyard scene.
This may have been done purposely by Hitchcock to create more of a Madeleine Spirit.
(at around 1h 14 mins) When Scotty is in the bell tower at the Mission San Juan Bautista and turns to see through the window Mrs. Elster falling to her doom, a panorama photo of the town can be seen behind her. In the rear right of the photo can be seen the mission itself, which Scotty is supposedly inside, minus its imaginary bell tower. The picture was taken from the hill to the south-west of the town.
Scottie and Judy drive through a grove of eucalyptus trees that is located south of San Juan Bautista on the way there from San Francisco.
Pop Leibel tells Scotty that Carlotta Valdez's benefactor built "the great house" for her in San Francisco's "western edition". However, Gough St is on the eastern side of San Francisco.
Scottie and Midge were supposed to have gone to college together but Barbara is much younger than Jimmie and looks much younger than him in the movie. Scottie is retired from the police and looks at least 10 or more years older than Midge.
In the opening rooftop chase, the crook, the officer and Scottie jump across from one rooftop to another. The distance is no more than 5 or 6 feet, yet when the officer falls and the shot shows him on the ground, the buildings are a full-alley's width apart, at least double the distance they supposedly jumped.
Among the many inconsistencies that the film is heir to there is also the necklace that Carlotta wears in the portrait. Elster would have had to have an exact replica made. But since he only needed Scottie to be fooled long enough to allow Madeline to "kill" herself, and he tells Scottie that Madeline never wore it anyway, there would be no reason for the jewelry to have been remade to begin with.
In Midge's apartment, the shadow of the boom mic is visible on the wall above Scottie's head as he gets up from the couch to leave. It rises as he does.
Gavin Elster mentions that Carlotta Valdes was 26 when she killed herself. However, her gravestone says that she lived from December 3 1831 to March 5 1857. That would make her 25, not 26.
When Scottie and Judy go shopping at Ransohoff's, a clerk comments that a nearby model wears Judy's dress size. The model is at least four dress sizes smaller than Judy; it's surprising that an experienced clerk would make such a mistake.
Scottie's friend says that the speedometer in his wife's car indicates she drove 94 miles. Speedometers show only speed; it is the odometer that shows distance driven.
At the redwood forest, Madeleine asks Scottie if the redwoods (Sequoia sempervirens) are the "oldest living things." He replies, "Yes." This is not accurate; bristle cone pines are the oldest living things. They live up to 5,000 years; redwoods only to 2,000 or so.