In "E.T., Go Home", Kodos is a murderous E.T.. In "Mr. & Mrs. Simpson", Homer and Marge are dueling husband and wife assassins. And in "Heck House", Ned Flanders uses the Seven Deadly Sins to scare some Halloween hoodlums straight.

Tropes:

• Adaptational Villainy: Kodos in the E.T. parody is basically E.T. if he were evil.
• Asshole Victim: After their previous attempts to conquer human society (and their success in "Treehouse of Horror VII"), Kang getting his head blown apart and Homer smothering Kodos (while disturbing) are rather fitting.
• Boom, Headshot!: In "Mr. & Mrs. Simpson", a disguised Marge nails Homer in the head with a shuriken. Despite temporarily descending into gibberish, Homer's perfectly fine once he yanks it out.
• Bond One-Liner: Parodied in "Mr. And Mrs. Simpson" as Homer plans to kill Kent Brockman:
  Homer (thinking): Now to think of a cool thing to say before I kill him.
  (beat)
  Homer (thinking): Ooh! That's a good one! But I don't have to say it aloud because no one's with me!
• The Cameo: One of Bart's pranks in "Heck House" is dropping Plopper on Homer's head.
• Cop Killer: Marge kills Chief Wiggum.
• Deal with the Devil: Ned channels Satan in order to gain powers to punish the children.
• Dirty Cop: Wiggum investigates Homer and Marge after they fight when they discover that they were both assassins. Marge shoots him with a crossbow to stop him, and his last words are "I would have accepted a bribe".
• Downer Ending: One of the few Halloween episodes to avert this. Kang's invasion and mass murder plot is foiled by the military. Homer and Marge reconcile their differences as assassins. And Ned really only scares the kids into behaving (although it's ambiguous if the deaths discussed under Seven Deadly Sins really happened, and Ned's fundamentalism is at full force).
• Exact Words: The plot of "Heck House" starts with kids deciding the choice between trick or treat should be theirs.
• Groin Attack: Moe receives one for stealing a stripper's cash.
• Guilt by Association Gag: In "Heck House", Bart, Milhouse, Nelson and Lisa are sent temporarily to hell, yet Lisa imply that she took no part in the chaos they wreaked (albeit she did nothing to stop them besides warning them, and she actually took part in the prank for Homer). She points this out along the way to hell: "I warned you, and yet my punishment is no less severe. That's odd."
• Insistent Terminology: Since Kodos was alive at the end, it was a vivisection and not a dissection. Homer soon changes this with a Vorpal Pillow.
• Leaning on the Fourth Wall: Marge, in the opening, bakes the various Fox characters she killed into a meat loaf with their various parts making up the title and credits. Homer takes and eats the last piece (with the “developed by” credits), saying “Mmm… developed by…”
• Mugging the Monster: Groundskeeper Willie repeatedly kicks his tractor out of frustration, causing it to turn into a Killer Robot. This quickly degenerates into Bullying a Dragon as Willie goes right back to kicking it after recovering from his surprise.
• No Fourth Wall/ Biting-the-Hand Humor: The introductory/ credit segments basically involves Marge murdering every Fox advertisement involving the NFL, American Idol, and FOX's popular dramas and feeding them to the family.
  • At the end, Ned tells us that we're going to Hell for watching FOX. "And that includes FX, FOX Sports, and our newest Devil's portal The Wall Street Journal."
• The Only One Allowed to Defeat You: Homer doesn't like it when someone else kills his targets. Justified because he's not paid for those deaths.
• Plagiarism in Fiction: Krusty's divine punishment is for stealing jokes.
• Riddle for the Ages: Whatever Homer thought about saying when he was about to kill Kent Brockman, he never said.
• Scare 'Em Straight: Ned in “Heck House” sets up the titular house into scaring the kids out of their mischievous ways. When his initially methods don’t work, he receives some divine help into using a more effective method.
• Seven Deadly Sins: "Heck House" parodies the basic principle.
  • Dr. Hibbert is rammed by a car for having Pride in his child's accomplishments.
  • Willie is beheaded for his Wrath by his transformed tractor.
  • Homer is transformed into spaghetti for his Gluttony and sliced through his hammock for his Sloth.
  • The remaining are covered by Moe's Lust for a stripper, his Greed for her money, and his Envy of those without groins after she subjects him to a Groin Attack.
• Shout-Out:
  • In "E.T. Go Home'', the hordes of Kang's troops emerge from the space portal via resurrecting broomsticks of "The Sorcerer's Apprentice".
  • In "Mr. & Mrs. Simpson" when Mr. Burns tells Homer to kill Kent Brockman, the picture of Kent Brockman is his mugshot which parodies Nick Nolte's infamous mugshot.
• Threat Backfire: Reminding the pranksters that she's the mother of their school's principal only makes things worse for Mrs. Skinner.
• Unexplained Recovery: When Homer is sliced through his hammock, he wonders what happened to his spaghetti transformation.
• Vorpal Pillow: Homer uses one to turn Kodos's vivisection into a dissection.
• Whole-Plot Reference:
  • "E.T. Go Home" is a parody of E.T. the Extra-Terrestrial.
  • "Mr. & Mrs. Simpson" is a parody of Mr. & Mrs. Smith (2005).