Blooper

Holly says that Kit sent his vow off in a helium-filled balloon that "he found while on the garbage route." This scene takes place well after the time when Kit was fired from the garbage route. Any gas-filled balloon he'd found then would have long since deflated.

At the beginning, Kit meets Holly after a long day as a garbage man, and his white T-shirt is spotless. Kit then asks Holly to take a walk with him, at which point the T-shirt is dirty.

At one point, Mr. Sargis is painting a sign whilst talking to Kit. As the scene progresses, the area he's working on becomes painted, unpainted, and then painted again.

Whilst Mr. Sargis is painting the billboard, his cigarette gets longer between shots instead of shorter.

The stone stack made by Kit near the end is inconsistent between shots.

Kit ostensibly hits Cato, a moving target, from hundreds of yards away with a shotgun blast. If he had loaded deer shot, it might just be possible, but Hollywood sometimes drastically overestimates the range and accuracy of firearms.

The rich man's maid is deaf. Why does he have a bell to ring for her? Actually, the bell is for the maid to signal to her employer, since she is mute as well.

Reading Star Hollywood magazine to Kit, Holly reports that Pat Boone is considering abandoning his career to finish his education. According to the tagline, the action in the film is taking place in 1959. Boone received received a bachelors degree from Columbia University in 1958.

Holly was reading an old magazine.

Just before Kit tells Holly her father is dead, his eyes move slightly.

The passenger train that passes Kit and Holly on the trestle is pulling Amtrak cars. Amtrak was not established until 1971, and this film takes place in 1959.

Although the film takes place in the late 1950s, there is a modern Ford car dealer's sign visible in one shot.

In the airport at the end, many of the troops are armed with M-14 and M-16 rifles (as indicated by the flash suppressors). Whilst these weapons would be contemporary with the filming, they are much later than the film's time frame (late 1950s).

Soldiers at the end are wearing fatigues consistent with the mid-1970s when the film was made, with subdued pin-on enlisted rank insignia on their collars (including a visible Specialist 4th Class in the front), and subdued name and U.S. Army tapes (black lettering on olive drab fabric tape) above their breast pockets. In the 1950s, enlisted ranks were worn full-size on their sleeves, unsubdued yellow on OD green (same as for their class-A green uniform), the U.S. Army tape above the left breast pocket would have been yellow on black fabric tape, and the name tape above the right breast pocket would have been black lettering on white fabric tape.

Set during the 1950s, an early 1970s era truck is visible in the background during an opening scene.

Car tires screech during the car chase at the end, even though they're on dust roads and sand.

For the last two lines in the discussion about the Fudgsicle, the actors' lips do not move.

Around 1:09:15 after Kit says "Forget it, it don't matter" a crew member can be seen at the right side of the screen.

A camera's shadow falls on Kit's back when Father and Holly find Kit in the house.

In a voice-over near the Montana - South Dakota border, Holly says "...at the very edge of the horizon we could make out the gas fires of the refinery at Missoula, while to the south we could see the lights of Cheyenne, a city bigger and grander than I'd ever seen." From anywhere along the border, Missoula would be over 600 miles to the west, and Cheyenne would be some 300 miles to the south; nothing short of a satellite view would allow you to see both at the same time.

In one of her voice-overs, Holly refers to the "mountains of Saskatchewan". There are no mountains in Saskatchewan, although there is a Mt. Saskatchewan in the Rockies.

When Kit records his confession on a record, he places coins in the machine and then flips the switch from 78 rpm to 45 rpm. The instructions above the switch clearly say "Before Inserting Coins Select Recording Speed." If he were following directions, he would have flipped the switch, then inserted the coins.

Holly is supposed to be 15 years old and still in high school, but Sissy Spacek was 24 years old when she made this movie and looks much older than a teenager.