We'll Have A Good Time Then - S6-E13
Continuity mistake: The picture Rachel takes of Shawn, Jack and Chet is not consistent with the framed picture Jack receives. When Rachel takes the picture, Shawn's necklace is sticking out of his shirt collar slightly and positioned to the right and he has a lock of hair draped over his forehead on the left side of his face. In the framed picture, his necklace is protruding from his collar more prominently and positioned to the left, he has no lock of hair over his forehead, and his left hand can suddenly be seen on Chet's left shoulder. Additionally, the framed picture shows Chet with his head slightly tilted back and showing his teeth as he smiles, but when the picture was taken, his head was level and he only had a slight grin with no teeth showing. (00:04:49 - 00:21:10)
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.