Plot hole: Emma is getting people to sign a petition to get tampon machines in the girls' bathroom. But in the episode "Mother & Child Reunion," when Joey and Caitlin are in there, there's a tampon machine. So you can see that they took it out or just neglected the fact to support the plot of this episode.
Other mistake: In the episode "The Mating Game," Ashley states, "Terry, sorry about last night." Unless she was with Jimmy and Ashley, because she is referring to when Ashley yelled at Terry. But that was 2 days ago, so why is she saying "last night" when it was 2 days ago?