It's Not Easy Being Green - S5-E16
Factual error: Boomhauer's car, Ms. Sally, has a Texas flag license plate on it. These plates were not issued until 1992, but Ms. Sally was driven into the quarry in the late 70's or early 80's.
Factual error: Kyle says he has to log on before school. The next shot shows "Monday 8 days later." 8 days before is a Sunday. (00:04:45)
Factual error: At the end when Ms. Finster tells Randall to give her the names of the kids involved with the ball incident, she says to list them in alphabetical order. The first name Randall says is "Dettweiler, T.J." But "Blumberg, Mikey" would actually come before that, and given what we know of Randall, this isn't the kind of mistake he is likely to make.
Fat Like Me - S5-E3
Factual error: When we see Tiffani and Stacy talk on the phone with Quinn (on the other end), we hear a call waiting beep from Quinn's end (but the camera still on the two girls' side) and Quinn mentions she's getting a call from Sandi. The mistake is only Quinn herself would have heard the "beep" and the other girls would have just heard Quinn's voice cut off with dead air for a second. Tiffani and Stacy should not have heard that "beep" like it was shown in the episode.
Wax Doll Castle Murder Case: File 3 - S1-E9
Factual error: The culprit merely drops a chandelier from the ceiling in an unplanned move. From that simple action, the whole building - a huge castle - catches fire so quickly you'd think it's made out of papier-mâche soaked in gasoline, not stone.