While movie covers four years of high school life ending with graduation in 1979 or 1980, scenes set during characters' freshman and sophomore years include scenes with marquees and signs advertising movies and Broadway plays (Starting Over, Dracula, Evita, etc.) that didn't open until their senior year.
While Bruno is talking to his father who is driving the taxi cab, Bruno's father is shown turning the steering wheel left, but the background shows that the car is turning right.
When Hilary is delivering her soliloquy of broken dreams in the abortion doctor's waiting room, her words and the movements of her mouth and lips are out of sync.
After four years of school, Doris Finsecker's little brother never gets any older.
When Mrs. Sherwood is arguing with Leroy about his homework, she wads up the same sheets of paper twice.
When Coco is doing her screen test for François Lafete, her hair is shown falling over her left shoulder as seen through the camera viewfinder. In the direct shot her hair is off the shoulder.
When Shirley shakes the metal gate after being told she wasn't accepted, the yellow slip in her hand vanishes between shots.
When Angelo punches the truck driver on the jaw, the trucker's hat comes off as the fight starts. The hat reappears on his head later in the fight.
When Leroy storms out of class, the chair he kicks falls over twice between shots.
When Bruno is in the taxi with his dad, the back window keeps changing from fogged up to clear.
When the kids spying on the girls break the pipe, the pipe comes off of the wall. In the next shot it's fixed back on.
When Coco gets out of the taxi and pretends to go into the hotel, the pavement goes from dry, to completely wet.
After Shirley is given her yellow slip back by the woman monitoring the stairs, the slip jumps from her right to her left hand between shots.
When Ralph auditions for the music teacher, the music teacher's actions with his pen are not continuous between shots.
When Lisa is talking with Miss Berg, Miss Berg goes to wash her hands. After she dries them, the washroom door keeps changing how far open it is.
When everyone is dancing in the street, a man in a yellow and black striped shirt changes from dancing on the street, to suddenly dancing on a car.
When François starts talking to Coco in the café, the donut on her plate and items on the bar next to her keep moving between shots.
When Coco is talking to François Lafete, she starts playing with her hair in one shot, but in the next shot her right arm is in her lap and her left arm is over the back of her chair.
At one point when Leroy is arguing with Mrs. Sherwood in the hospital, her hands are up by her shoulders but in the next shot they are down.
The "Palace" sign outside Montgomery's room flashes On-Off, but when Doris and Ralph are kissing and Montgomery leaves, the light pattern outside is more complex than a simple flash.
At about 15:00, while Ralph is explaining that the reason he wants to attend the school is because Freddie Prinze went there, we see Michael open and begin to eat from a soup container. Then in the reverse shot we see Michael (from behind) not eating. Then back to the original front shot with Michael eating again.
Reflected in various people's glasses.
When the father and son are talking in the taxi, his turns of the wheel do not cause the taxi to turn, as revealed by the view out the window, which of course is not real.