Near the beginning of the movie, Michel is driving in the countryside, down a lane with trees on either side. This is shown from outside the car. When they cut to the view from inside the car, there are no trees.
After Michel and Patricia's discussion about "grief" concludes, Patricia's cigarette length changes inconsistently. It's initially long, but after she says "That's me", it's quite short; then, as she throws the hat off her head and tosses the cigarette, it again is long.
During Patricia's lunch with Carl, the cars in traffic behind him jump around as he talks, revealing film edits.
After being dropped off at the dress shop a by Michel, she comes out as he is reading the newspaper in the car. She is talking with a who man trails her out of the shop. Just as she steps off the curb, there is a cut, and she is immediately completely across the street, next to Michel at the driver's door.
The first time Michel is driving Patricia, the background scenes abruptly change after camera cuts.
When Patricia is first picked up by Michel in a car she asks him, "Don't you have the Ford anymore?". Although some may interpret this as a reference to the Ford Thunderbird Michel steals much later in the movie, this is unlikely to be the case: Michel is shown to be stealing multiple cars throughout the entire film, so this is likely to be a different car she is referring to.
During street shots, countless passersby look at Patricia and Michel and stare into the camera, revealing that the shots were made without filming barriers and simply used street pedestrians in place of extras.
When Patricia (Jean Seberg) is going up the escalator, a plant beside it can be seen moving, as if knocked by the cameraman going up in front of her.