Chekhov's Gun: The long-abandoned subway is mentioned in the "Springfield of Tomorrow" film.
Hands-Off Parenting: When Homer and Marge grew tired of Bart manipulating them, they opted for this until they learned of his plan to destroy Springfield with the abandoned subway.
Noodle Incident: Bart was able to cheat on a rectal thermometer. If he doesn’t want to talk about it, then one rather not asks.
Out of Character: Homer is unusually strict in this episode towards Bart. He almost sadistically wants Bart to do more homework than is required of him, and refuses to let him take even a short break despite him actually doing it.
Kid Has a Point: Nelson explains to Bart why he isn’t getting his fix and Lisa at the end.