Factual errors: Nathan is seen wearing a blue shirt under his white uniform. A teammate is wearing a white undershirt. In the rules of national high school basketball, it is illegal for teammates to have different colored undershirts as well as having a color that is not the same as their uniform.
Continuity: In the episode "Life As a Glass House," Haley and Nathan are studying. Haley gets up to leave, she puts her bag on across her chest. A few seconds later she is seen, putting her bag on again except she keeps it on her right shoulder. And when she leaves, the bag is once again across her chest.
Continuity: Lucas's tattoo disappears and reappears after the car crash. Most of the time it is covered though because he is wearing his basketball uniform.
Incorrectly regarded as goofs: Peyton's full name (as seen mentioned many times) is Peyton Elizabeth Sawyer. Peyton says to Haley at one point that Brooke has been calling her "Peyton Marie Sawyer" because of the way she was acting. Peyton then explains that the initials spell PMS revealing that it's just a joke between her and Brooke. Therefore, Peyton's middle name does not change at any time in the series.
Continuity: Jamie was born on the day of graduation in the fourth season and then in the fifth season they celebrate his birthday. The problem is that school is obviously still in session since there are eleven more basketball games left in the season. So they celebrated a few months early.