The song that plays when Bart and Milhouse abuse "Zombie Homer" is Edgar Winter's "Frankenstein."
The title, "Crook and Ladder", is a parody of Hook & Ladder, a fire engine.
When Mr. Burns jumps out of the window, he floats like the feather at the beginning of Forrest Gump, with similar music. The last episode, where Forrest Gump has been referenced in Simpsons, was "Gump Roast".
The song that plays during the montage of Bart, Lisa, and Maggie looking sadly at Homer is "Sad Eyes" by Robert John.
The scene where Homer wakes up in bed next to John Lennon is in reference to Lennon & Ono's "Bed-In for Peace", a non-violent anti-war message in the 1960s.
Larry Flynt (former publisher of Hustler) is mentioned by Lisa as the publisher of Smothering Mother magazine.
Nappien, taken by Homer to cure his insomnia, relates to the current problems of people's over-reliance on pills & medication, such as sleeping pills. The problem of prescription drug abuse is highlighted by Homer's reply to the Flanders "Kids, you are confusing Drugs with ddrrruuuuugs" and Homer's line about being just like 80% of America: whacked out on prescription drugs. Also, Lisa says "I've read that people do strange things in their sleep when they've taken Ambien... I mean Nappien." Ambien is a brand name for Zolpidem, one of the most common insomnia pills. Homer's own zone-out could refer to the well-publicized case of Patrick J. Kennedy, who drove his car and even participated in a United States House vote while under the influence of sleep medicine.
The commercial for Nappien shows a dove, much like the butterfly from the Lunesta commercials, flying into people's bedrooms, and landing on them, causing them to fall asleep. However, the dove excretes a sleeping pill into the person's mouth to achieve this effect.
The movies jackets given free to the firefighters by Rainier Wolfcastle is a play on some of Arnold Schwarzenegger's movies as well as other contemporary films. (E.g. "Total Explosion" "Total Recall", "Frankenberry wears Prada" "The Devil wears Prada".)
The man Homer fights during the "Zombie montage" previously made an appearance in season 16's Pranksta Rap and is still wearing the same chain stating it to be "Thursday the 20th." The rapper from "Pranksta Rap" who was used to verify the time can be seen in the background of the fight.
The Simpson family has a videotape of C.H.U.D.
If you look closely when all the video taps are knocked down as dominoes, you can see Matt Groening's signature under Homer's face on domino.
Apu tricks Homer and Moe into thinking he was killed and reincarnated as a cat. Afterwards, he says "You've just been Apu'd!", which is similar in context to Punk'd.