YMMV / The Simpsons S 11 E 4 Treehouse Of Horror X
"Funny Aneurysm" Moment: A Simpson causing the death of a Flanders family member stops being funny after the episode "Alone Again, Natura-Diddly (only replace "Marge" and "Ned" with "Homer" and "Maude")
Even worse is when the Y2K bug takes over, Dick Clark says "Oh, no, it's happening" and melts to reveal a robotic skeleton (a la the T1000 in Terminator 2: Judgment Day). Back then, it was just a joke about Dick Clark's seemingly perpetual youth. Now, it's not so funny thanks to the stroke he had in 2004 and his death in 2012.
I Am Not Spock: Lucy Lawless grabs Bart and Lisa and flies them back home. On the way, Lisa notes that Xena can't fly. Lucy reminds them she's not Xena. Apparently Lucy Lawless can fly normally.
Old Shame: As heard on the DVD Commentary of this episode, the writers regret putting both Spike Lee and Al Sharpton on the rocketship being sent into the sun. In hindsight, they said they would have preferred to put George Steinbrenner on the plane instead.
Values Dissonance: The final few minutes of "Life's a Glitch, and Then You Die", where Mel Gibson and Ron Howard are among the A-listers on the Mars rocket, while Spike Lee is on the rocket to the sun. The former can be excused at the time on account of having been a recent guest, and still being a few years away from his public fallout. Ron Howard is a little more spotty though; while he has had a reputation as being a perfect gentleman, even then he was hit or miss at the box office, and his better films still being a couple years off. The worst that can be said about Spike Lee, by contrast, is his oft-polarizing nature, but few can deny his level of artistic integrity, or his level of accomplishment. The writers at least have regretted putting him on the latter rocket in retrospect.