Homer discovers that his runaway radical mother has come back and promises that her days of running from the law are over, which Homer doesn't believe. However, he soon regrets it when Mona dies during the night, and leaves Homer a bizarre last request.
* AntagonistInMourning: Grampa has always wanted to dance on Mona's grave after she left him, but doesn't feel like it now that her death finally happened.
* ChekhovsGun: Every single thing Mona left on her will (and her diamond earrings, which Lisa took from her corpse because she left her nothing of actual monetary value) ends up being used to stop the silo launch in a PlotTailoredToTheParty fashion. As well, Homer's brick-and-chain "home defense" gadget is used to fight off some Mooks.
* DyingAlone: Mona dies alone in front of the fireplace.
* HalfwayPlotSwitch: More like "final act switch", but still most of the episode is Homer being sad about Mona not being part of his life in one way or another (her being constantly on the run, then dying), then trying to honor her final wish... and then it turns out that Mona set up Homer to raid Burns' super-secret missile silo, turning the episode into a ''Film/JamesBond'' pastiche for about five minutes.
* MomentOfSilence: The moment when Homer realizes that his mother has passed away is pretty effective. There's no music and the only sounds heard are the crackling of the firewood and crickets chirping.
* OOCIsSeriousBusiness: When Homer puts down pie, you know things are getting serious.
* ParentalAbandonment: Mona has abandoned Homer several times, once when he was a child and twice in his adult life. By the time she returns for good, he's so fed up with her leaving to be a radical protester, he wants nothing to do with her.
* PartingWordsRegret: Homer's last words to Mona were words of anger because she abandoned him so often.
* ThanatosGambit: Mona pulled one with her dying wish to make Homer stop a nuclear silo which nearly gets him killed.
* TheUnfavorite: Lenny is this for his mother who prefers Carl and wishes he was her son.
* WhamLine: At the end of Homer's apology:
-->'''Homer:''' Mom? (''[[KilledOffForReal no response]]'') ''[[TearJerker Mom?]]''