Continuity mistake: In the beginning of the series, Haley's big family is brought up often, implying that she has 3 brothers and 3 sisters. When her mom visits her, Taylor and Quin to announce that she is dying, there is no mention of or visit from any other siblings and Lydia talks about those 3 as if they are her only children.
Continuity mistake: When Deb is telling Nathan that she started the dealership fire they show a reconstruction in which Deb has long hair but on the 1st episode of series 3 (the fire) you see her with shorter hair same as last episode in series 2.
Continuity mistake: Firstly when they start their senior year and you see Lucas and Hayley looking at their predictions, longish hair and no beard, then it cuts to them at school and you see Lucas with a hair cut and a beard,then in the next scene, he has no beard and long hair.
With Arms Outstretched - S1-E9
Continuity mistake: When Lucas is showing Keith his tattoo, in each shot the sleeve of his shirt keeps changing from rolled up to rolled down.
What Is And What Should Never Be - S1-E20
Continuity mistake: Haley's lipstick gets noticeably thicker and thinner between different shots when she's talking to Nathan (when she drops over some groceries).
The Games That Play Us - S1-E22
Continuity mistake: Throughout the entire episode, Lucas' hair length ranges from being short to long.
The Truth Doesn't Make A Noise - S2-E2
Continuity mistake: Early in the episode, Lucas is listening to his Ipod on the river court. Later, Keith comes to his house and tells Karen that Lucas left it in his truck.
Continuity mistake: In the final scene of the episode Brooke joins Mouth at the side of the Rivercourt, but when the camera switches to further away it shows Brooke walking towards Mouth and joining him again.
When It Isn't Like It Should Be - S3-E18
Continuity mistake: Nate touches a photo on the wall of a smiling late Keith, with Lucas as a small boy. Next shot, Lucas taps on the door to let Karen know the gang is taking off, but there's no response. Next shot shows Karen sitting the other side of the door, grieving, holding that same photo of Keith and Lucas. (00:02:45)
Continuity mistake: When Lucas is with Keith at the graveyard in 4-10 and Brooke is standing in front of "Peyton's" tombstone, it says she died on March 1, 2006. Keith notes that she died on the day of the shooting. However in this episode Lucas visits Keith's grave where his tombstone says he died in January 2016.
Prom Night at Hater High - S4-E15
Continuity mistake: In this episode a sex tape shows a fling between Brooke and Nathan, and it is supposed to be from the past, but Nathan's hair is much longer and so obviously older in the video that it looks like it could have been filmed the night before, not from when he and Peyton were together.
All of a Sudden I Miss Everyone - S4-E21
Continuity mistake: When all of the girls dance to the Spice Girls song "If You Wanna Be My Lover", during this scene Haley's shoes repeatedly change from high heels to trainers whilst she is dancing.
4 Years, 6 Months, 2 Days - S5-E1
Continuity mistake: When Hailey finds Nathan asleep on the couch and cleans up his mess she originally has 2 beers and a bottle of tequila, but in the next shot she has beer, tequila and chips.
Please, Please, Please Let Me Get What I Want - S5-E8
Continuity mistake: When nanny Carrie is hungover and talking to Nathan she has a pot of coffee which changes volume throughout the scene, from almost full to almost empty to half full again.
Continuity mistake: Nathan is watching Haley walk down the aisle, but when the camera pans to Nathan for a face shot, it is Lindsey's head that goes past the camera, and Lindsey he is looking at. (00:18:50)
Searching for a Former Clarity - S6-E18
Continuity mistake: In the legendary "a random dog eats Dan's heart" scene, the cooler and its lid keep changing position between shots when they fall on the floor.
Every Picture Tells a Story - S7-E19
Continuity mistake: Nathan and Jamie are apparently playing Rock Band but when it cuts to clips of them dancing the TV is off.