For Love and Apartments - S7-E2
Other mistake: When Cory is trying to get Topanga's parents to reconcile, Topanga's mother mentions to her ex-husband about the "beautiful child they've made." Given that she says "child" in the singular, this can only refer to Topanga. However, the season 1 episode She Loves Me, She Loves Me Not established that Topanga had an older sister named Nebula. So the mistake is that either the show is acting like a character that was firmly established never existed, or Topanga's mother doesn't realise she has at least two children. (00:15:32)
Chosen answer: In the present day, with the United States abiding by more stricter school health laws, for the most part this wouldn't be in school cafeterias as many cannot even have carbonated beverage machines now. However, in the 90s when the show takes place, it wasn't unheard of for there to be coffee machines in the cafeteria of small schools where the teachers eat with the students as we see them do often in the show. The idea being that the cafeteria was small enough so a teacher or hall monitor could catch a student before they could drink the coffee.