The title of Married to the Blob, which is a reference to the 1988 comedy film Married to the Mob and the plot to be a parody of the 1988 monster horror film The Blob, would later be used for Married to the Blob, episode 10 of Season 25, 7 years, 2 months and 1 week later on Sunday, January 12, 2014.
The 50 Foot Lenny and the Invisible Carl are a reference to the 50 foot woman and the Invisible Man.
The title You Gotta Know When to Golem is a reference to the lyrics "You've got to know when to hold 'em" from the song The Gambler. The plot is a parody of the 1915 silent horror film The Golem.
In the segment The Day the Earth Looked Stupid the General store kwickee & son has banner (today's super-Lotto jackpot: $18) 18$ in 1938 became $245.65 in 2006 (in 2016 $298.65) because inflation adjustment also newspaper Springfield Shopper price two cents ($0.02) in 1938 and today half dollar a newspaper.
After Homer eats some fat German men at an Oktoberfest, he remarks "Must eat more fat people. Thank God I live in America."
In the segment You Gotta Know When to Golem, the female Golem is made of Play-Doh! (as you can see Play-Doh! cans on the grass after Marge made her).
When Kang and Kodos invaded Earth, Kodos remarks that "we had to invade! They were working on weapons of mass Disintegration!" which is a reference to how American soldiers invaded Iraq because George W. Bush claimed they were working on Weapons of Mass Destruction.
The fact that "The Day the Earth Looked Stupid" lapses over three years is a commentary on, as many others have suggested, the US occupation of Iraq. Operation Iraqi Freedom, which later turned into Operation Enduring Freedom, began in 2003; this episode aired in 2006, three years after the beginning of the occupation. Springfield, after internal hysteria, is invaded by an external force, and, therefore, is a model of Iraq. Kang and Kodos are, obviously, the American soldiers.
Originally, "The Day the Earth Stood Stupid" was supposed to end with one of the aliens commenting on how the abandoned Springfield looks the same way as Iraq will be in the future. While the FOX censors and executives had no problem with the line, the writers still had it removed, as they thought the reference was too blatant.
Halloween name for Al Jean was "Al "July 27th, 2007" Jean". This is a reference to Simpsons Movie release date.
"Treehouse of Horror V": Uter gets eaten and a character (Edna in the Treehouse of Horror) gains weight. Also, Oktoberfest plays a role in one of the episodes in direct relation to at least one German character being devoured.