Continuity mistake: This episode is during Christmas time and it's Alan's birthday, but it was mentioned in "Honesty Night" that Alan's birthday is June 14th.
Other mistake: At the beginning of the episode, Eric talks about how Alan's Navy background will cause him to use any means necessary including torture to find out about his birthday party. Cory chimes in and states that Alan was a cook in the Coast Guard. The plot of the Season 1 episode Kid Gloves concerned a necklace Alan gave Cory for his birthday, which Alan himself earned for placing second in his weight class for boxing in the entire Navy. So either Cory doesn't correctly remember his own father's military background, or the show needlessly retconned it. (00:00:43)
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.