In this year's Halloween special, Marge accidentally kills Ned Flanders, Bart and Lisa become superheroes, and Homer causes a technological apocalypse when his work computer is the only one that isn't Y2K-compliant.Airing on Halloween Night itself, it was notably the last annual Treehouse of Horror special to consecutively air in October, something which would not happen again for another full decade.
"Tropehouse Of Horror X":
- Adam Westing: Tom Arnold, who admits he's a lousy celebrity.
- Artistic License – Astronomy: After realizing that he and Bart are being sent into the sun:Homer: The sun?! But that's the hottest place on Earth!
- Breather Episode: "Desperately Xeeking Xena" is a light-hearted superhero parody sandwiched between the traditionally spooky " I Know What You Diddily-Iddily-Did" and the pessimistic Black Comedy of "Life's a Glitch, Then You Die".
- Comically Missing the Point: Lisa attempting to be sarcastic to Homer.Lisa: Well look at the wonders of the Computer Age now.
Homer: Wonders, Lisa? Or blunders?
Lisa: I think that was implied by what I said.
Homer: Implied, Lisa? Or 'implode'?
Lisa: Mom, make him stop!
- Continuity Nod: During the opening sequence, all the Simpsons are dressed as various creatures they've been turned into during several past Treehouse episodes.
- Damsel out of Distress: Lucy Lawless.
- I Am Not Spock: Invoked in "Desperately Seeking Xena": She's not Xena, she's Lucy Lawless. Despite dressing like Xena anyway.
- Killed Offscreen: Unusually, it's Homer who was killed offscreen by a werewolf Flanders eating him.
- Also in "Life's a Glitch," Homer and Bart eject themselves into space, where they inflate like balloons and then pop just off-screen.
- Not So Above It All: Marge allows Homer to go looting when he promises to loot her a present.
- Of Corpse He's Alive: The scene from "I Know What You Diddily-Iddily-Did" with Homer fooling Maude into thinking Ned's still alive is even the trope's image source.
- Oh Crap!: Oh no, Rosie O'Donnell!
- Ominous Fog
- Sadistic Choice: When the world ended, there was a rocket sending the smartest people to Mars. Lisa got to go but wouldn't be allowed to take both of her parents. She quickly chose her mother as soon as the soldier mentioned the restriction.Homer: Goodbye, Lisa. Remember me as I am — filled with murderous rage.
- Screw This, I'm Outta Here!: In "Life's a Glitch", Bart informs Homer that, even though they might be on a rocket with Rosie O'Donnell and Pauly Shore, amongst others, they will be dead in 5 minutes (as they will crash into the sun). Homer is quick to react to this news."NOT FAST ENOUGH!"
(Presses button and ejects himself and Bart into space)
- Shout-Out: To I Know What You Did Last Summer - though with no explanation as to why Flanders is wearing the slicker and carrying a fish hook.
- Marge mentions that the kids are vulnerable to Kryptonite.
- Skewed Priorities: Lucy Lawless would rather get captured and forced to marry a super villain than bare her breasts to a crowd of Xena fans.
- Superhero Episode: Stretch Dude and Clobber Girl protect Lucy Lawless from The Collector.
- Take That: The rocket sent on a collision course to the sun with the apparent purpose of getting rid of the worst/most useless people on Earth, which include such celebrities/familiar 1990s faces as Ross Perot, Dan Quayle, Tonya Harding, Al Sharpton, Courtney Love, Spike Lee, Tom Arnold, Pauly Shore, Rosie O'Donnell and Dr. Laura Schlessinger.
- The Comic Book Guy saying that he fell for a ruse "So hackneyed it would make Stan Lee blush!"
- Totally Not a Werewolf: Ned Flanders!
- A Wizard Did It: This episode is the Trope Namer, which comes from a line from Lucy Lawless (the actress who plays the titular character of Xena: Warrior Princess) as a quick way to answer fans complicated questions.Professor Frink: (after Lucy Lawless established the phrase) But in episode AG4 —
Lucy Lawless: Wizard.
Professor Frink: Aw, for glaven out loud...
- Your Head Asplode: In "Life's a Glitch, Then You Die", Homer and Bart realize they're on a rocket that's heading into the sun with various washed-up and overall terrible celebrities. Rather than spend another five minutes with Rosie O'Donnell and Tom Arnold, they eject themselves into space, where their heads swell up as they give a blissful sigh of relief and then pop offscreen.