Other mistake: Lucy's drivers license says her birthday is in January but she was conceived on Valentine's Day.
Revealing mistake: Throughout the entire series there is one staircase upstairs and two downstairs. And, they more than likely are not the same staircase because the two downstairs are on opposite ends of the house.
Ruthie: You're the worst babysitter I ever had.
Simon: That's not what you said two hours ago.
Ruthie: Yeah, well that was before you made me wear the staircase.
Trivia: This episode has the infamous scenes in which Mary wants Matt's help with kissing. Supposedly, the original script involved the siblings actually kissing for practice, but Jessica Biel (playing Mary) and Barry Watson (Matt) refused to do it.