Factual error: In this episode, Eric and Cory stop in Pottstown, Pennsylvania on their way back to Philadelphia. Cory protests, reasoning that stopping there is pointless because they are only three hours from home. Pottstown is roughly 40 miles from Philadelphia. It certainly wouldn't take three hours to get to one location from the other under normal driving conditions.
Continuity mistake: At the end of the episode, when Cory and Topanga are kissing, Shawn says "Hey, I'm talking to you", hits Topanga on the arm and her hair gets messed up. When the shot changes to a wider view, her hair is not messed up. The position of Topanga's arms wrapped around Cory also changes.
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.