Revealing mistake: While Lucas is in the shower and someone steals his towel and clothes, he walks out into the hallway holding two basketballs. When he turns toward coach Durham you can tell that Lucas has on nude colored underwear.
Revealing mistake: Brooke takes the towel off Nathan, but you can tell that he is not actually naked and is wearing boxers.
You Can't Always Get What You Want - S2-E4
Revealing mistake: When Dan and Lucas are racing Felix, from one scene to the next where the actors are replaced by stunt doubles. Close up, they are Paul Johansson and Chad Michael Murray, but from far away when the actual driving is happening, they are not the same people.
Revealing mistake: Haley's pregnancy pad is visible when she raises her arms while lying on the table. (00:21:15)
Hate Is Safer Than Love - S5-E17
Revealing mistake: When Brooke goes in to the NICU to see Angie after her surgery, it is a doll in the incubator.