The Distance - S2-E1
Factual error: In the first episode of season two you see Teresa with Ryan, yet she has no bump. Season one ends at the end of the school term and season two starts off just before the school term. Therefore there's been about two and a half months of school holiday plus the time between her sleeping with Ryan and discovering she's pregnant and Ryan leaving for Chino with her - therefore she should be showing some signs of pregnancy in early season two.
Suggested correction: Not necessarily, some women, even very few, don't show until the 7th month or only put on baby weight of around 7-9 pounds.
Factual error: How exactly does Seth unlock the door? The entire purpose of locking the storeroom is to keep mall customers out so they won't steal things, not to keep people in there, so there is no way it was only lockable from the outside. If it was a key operated lock, why would someone just leave their key in the keyhole for someone to take? There is no explanation for Seth being able to unlock the door.
The Gamble - S1-E3
Continuity mistake: When Ryan's lunch tray gets knocked out of his hands in jail and the guy pushes him onto the table, a fork appears in his hands with no time to pick it up.
Continuity mistake: Marissa walks inside, pulls off her dress, and puts on her pink top, doesn't put on any pants but in the next shot she's wearing jeans.
The Shower - S1-E25
Continuity mistake: When Ryan and Marissa are play-fighting in the Balboa Bakery, their arms change position repeatedly.
The Escape - S1-E7
Continuity mistake: When Marissa and Ryan are out at the vending machine, Marissa hasn't got her cell phone with her, and she hasn't got any pockets, but then later when they are heading back inside just as it rings she is holding it.
The Heights - S1-E9
Continuity mistake: Jimmy brags to Marissa that he is having an "actual phone line" installed that day, when in the episode before he is seen using a cordless home phone when Julie rings him after Marissa ran away from the hospital.
Continuity mistake: When Oliver is singing along to "It's Not Unusual" by Tom Jones and is dumping all the pills onto the coffee table, the pills go from being all mixed up to in colour co-ordinated piles, and back and forth.
Revealing mistake: If you look closely, a bit into the fight you can see that Hailey is not actually putting any trash inside the trash bag. She is just going through the motions.
Continuity mistake: The lighter and packet jump into The Nana's hands after she stubs out her last cigarette.
Continuity mistake: When Summer screens the call from Seth at the airport, her phone opens without her flipping it.
Factual error: Marissa tells Ryan that she "has never slept with anyone before" (in the literal sense), which is not true as she and Ryan slept together (in the literal sense) at the motel in Tijuana, and then woke up with their arms around each other.
The Escape - S1-E7
Continuity mistake: When Summer and Seth are arguing during the car trip to T.J., Summer's hands move from touching her hair to holding her bottle when she says, "You're Jewish?"
Plot hole: Ryan says that he has left his watch at the motel after sleeping with Theresa, and goes back to get it. However, at the end of The Goodbye Girl (the episode before) he is seen wearing it as he gets out of the car to go and talk to Theresa, only to find she's gone back to Chino. The whole story of Ryan and Seth going back to get his watch from the motel is just an excuse for them to discover the whole Luke/Julie affair.
Character mistake: Marissa said to Ryan (in episode "The Brothers Grim") that the last time she was in Chino, she "saved his ass". She was referring to Thanksgiving, but that's not the last time she was in Chino. The last time she was in Chino was in "The Nana" when she ran there after finding out about Luke and her mother's affair.
Suggested correction: She saved his ass when she talked to Eddie about letting him stay. So her phrasing is correct.
Continuity mistake: At the start, Summer and Marissa are talking about the weekend. Summer says something like, "I'm going mad over Seth Cohen." The camera swaps from Summer and Marissa. We see Summer first with her hair in front of her ear, then when we cut back after seeing Marissa, Summer's hair has gone to behind her ear.
The Best Chrismukkah Ever - S1-E13
Continuity mistake: When Marissa goes to see the psychiatrist, she sits down and puts her jacket on the arm of the chair. When the shot changes, her jacket is on the other side of her.
Continuity mistake: At the beginning of the episode, Kirsten and Ryan are sitting at the table. From the front you see Kirsten pick up her coffee cup. In the behind shot you see her put it down and in the next shot, which is from the front, the cup is still in her hand and she's putting it down again.
Continuity mistake: Ryan walks into Oliver's hotel room twice; there are two shots of him moving from behind the hotel room to come in front of it, separated by six seconds. (00:37:30)
Continuity mistake: When Ryan and Seth arrive at school Marisa goes and hugs Ryan. As she hugs him she puts her hand on his shoulders as if to hug him around the neck, or just to let Ryan hug her, but in the next shot her hands are around his waist.