Continuity mistake: When Mr. Roper tries to explain to the girls and his wife what he was doing in Jack's bedroom, watch over Mr. Roper's left shoulder on the shelf. The number of yellow cans on the shelf keep alternating between one and two cans throughout several minutes.
Continuity mistake: In the first two seasons, there are 3 bedrooms upstairs: Mama's, Fran's, and Sonja's. But after Buzz and Sonja move out and Aunt Fran dies, Bubba moves in and takes Aunt Fran's room. Vinton and Naomi are still in the basement complaining that they wanted Fran's room. However, originally there was another room upstairs, Sonja's room, that disappeared.
Continuity mistake: When Jack speaks to Michael and Jin, as they build the raft, and then when he walks up the beach and inquires about Sawyer's trouble with his head, the backpack that Jack carries on his back is nylon, black/green with white trim. Yet, when Sawyer asks, "Sensitivity to light, that bad?" the backpack is suddenly transformed into solid black leather, of an entirely different style. Then, in following shots it jumps back and forth. (00:16:40)
Plot hole: In this episode all the students say Hollywood Arts has never had a prom before. But in the first episode, 'Pilot', Rex says to Cat after she runs out to tell Tori, Robbie, Andre and him that Sikowitz wants them to come back into the classroom, "Just like you wanted a date to the prom last year."
Plot hole: The very ending scene where Peter (in this version died in the ice as a boy so Walter's wife never met him) takes off some of the dust covers then picks up a toy airplane. The toy airplane he got as a child from ... Walter's wife when she was trying to placate him in an earlier episode for trying to run "home". This toy airplane wouldn't have been his as a child in this version of the universe. (00:42:00)
Continuity mistake: When Jax and his crew meet up with a Hispanic gang to sell them guns and are outnumbered, they run in the station wagon. The run the station wagon through a gate and roll it, destroying the front end, but magically the station wagon's front end appears with little damage afterwards. (00:27:15)
Continuity mistake: During the episode when Claire and Phil do their warm-up before racing each other, their children Alex and Luke arrive from school. They get down from the car, and the car takes off and goes away. But in the 2nd shot we can see that same car parked in front of them. (00:17:00)
Audio problem: When Michael is forced to do "errands" for Brennen, they stop by Jonathan Carver's house to get numbers from him for a voice key. The code played back at the facility is 71348. He says "3" in a medium pitch (tone) at the house, but it is high pitched when played back at the facility; he says "8" in a medium pitch, and it's also high pitched later. And finally he says "9" in a low pitch and it's played back medium pitch. Also very obvious is the fact that Jonathan never says "1" or "7."