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.
Tropes:
- Artistic License – Physics: During the ESPY Awards, Lance Armstrong is offended by a joke Fozzie Bear makes about his trousers, grabs the Fozzie puppet and throws it across the room to reveal a single arm and hand underneath. However, the way the Fozzie puppet is designed in real life is that the performer uses his right hand to work Fozzie's mouth and his left to operate Fozzie's left arm and hand (as he's a glove puppet, as opposed to a puppet like Kermit, whose arm is controlled via a rod), and Fozzie was seen using his left arm before Lance threw the puppet away.
- Antagonist in Mourning: 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.
As he walks away, one can clearly hear that he's wearing tap-dancing shoes. - Batman Gambit: Mona’s posthumous plan to destroy Burns rocket is this to an insane degree. It not only relies on several people acting exactly the way she expects, but is even dependent on the weather itself cooperating with the scheme.
- Black-and-Grey Morality: Mr Burns is his usual villainous self but, while Mona is certainly the more moral of the two, she is willing to use her family as unwitting pawns in a potentially life-threatening scheme to foil his plans one last time.
- The Bore: Marge considers listening to the music radio on the way to the mall to be fun.
- Bury Me Not on the Lone Prairie: The entire latter part of the episode revolves around Homer deciding, as a way of trying to show he's sorry, to follow Mona's instructions on how to dispose of her ashes. The third act switch occurs because it turns out that the specific time and place Mona ordered for the disposal would lead her ashes to be picked up by the wind and dumped on the air intake of Burns' rocket, shutting down its launch capabilities.
- Cerebus Retcon: Homer became the insatiable Big Eater we've seen throughout the series to cope with the frequent absence of his mother over the course of his childhood.Homer: You left a hole in my heart that could never be filled, so I filled it with food, but I'm never full.
- Chekhov's Gun: Every single thing Mona left on her will (and her diamond earrings, which Lisa took off her nightstand because she left her nothing of actual monetary value) ends up being used to stop the silo launch in a Plot Tailored to the Party fashion. As well, Homer's brick-and-chain "home defense" gadget is used to fight off some Mooks.
- Continuity Nod: Mason Fairbanks, who was Mona's former lover (from Homer's Paternity Coot) is present in her funeral.
- Crazy-Prepared: Mona left many things for every family member to use for her last hippie action against Burns. What only cements this is the fact she was counting on Lisa, of all people, to steal her diamond earrings to use to burn the bag she gave to Marge to start a smoke alert in the silo. She knew very well Lisa wasn't going to be satisfied just inheriting her nature as a Granola Girl.
- Dies Wide Open: We don't see Mona's face after her death, but upon finding her in the armchair Homer first thinks she fell asleep...with her eyes open.
- Dying Alone: Mona dies alone in front of the fireplace.
- Halfway Plot Switch: 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 James Bond pastiche for about five minutes.
- I Am Not Your Father: Inverted — Homer is fed up with Mona coming and going and only using him for her Granola Girl schemes and tells her she can spend the night, but come the morning she's to Get Out! of his home and forget she ever had a son. And then she dies during the night.
- Moment of Silence: 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.
- Named Weapons: Homer has a homemade weapon comprised of a cinder block and a chain. He refers to it as “The Defender”.
- O.O.C. Is Serious Business: When Homer puts down pie, you know things are getting serious.
- Oh, No... Not Again!: When Homer starts tearing apart the stuffed hippos that Bart programmed with insults, Lisa hesitantly tells Marge they have a "Code 4".
- Parental Abandonment: 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.
- Parting-Words Regret: Homer's last words to Mona were words of anger because she abandoned him so often. All of the plot past that point is led by Homer trying to make amends for that.
- Pop-Culture Pun Episode Title: The episode's title refers (once again) to The Mona Lisa.
- Rage Against the Heavens: Minor example. When Homer notices the silo and what the ashes did to the rocket, he figures out that he became a pawn for yet another of his mother's anti-Burns schemes and he lets out an enraged "you used me again, Mom!!" to the heavens above.
- Really Dead Montage: The very last thing the episode shows before showing an
In Memoriam card and cutting to credits is one of these for Mona. - Robbing the Dead: Lisa steals the diamond earrings from Mona's nightstand because she didn't like the fact that Mona hadn't left her any actual physical belongings on her will (she had left her the mission to carry on as a Granola Girl for her).
- Self-Destruct Mechanism: Homer inadvertently activates the base's self-destruct sequence with his brick-and-chain gadget shortly after defeating the guards. Fortunately for the Simpsons, Homer escapes and reunites with them.
- Thanatos Gambit: Mona pulled one with her dying wish to make Homer stop a nuclear silo which nearly gets him killed.
- The Unfavorite: Lenny is this for his mother who prefers Carl and wishes he was her son. Lenny's apparently also this to Moe as Carl passes on a message from her to Moe saying that Lenny's mom loves him.
- Wham Line: At the end of Homer's apology:Homer: Mom? (no response) Mom?
- You're Not My Father: Of the "mother" variant, Homer telling Mona to leave come the morning because he's fed up with her scheming and that he doesn't need her anymore.
