The chant Panty and Stocking say during their Transformation Sequence is very similar to Hell Girl's chant before she ferries people to hell.
Then there's the chant from the dub: "O evil spirit born of those drifting between heaven and earth, may the thunderous power from the garments of these holy, delicate maidens strike down upon you with great vengeance and furious anger..."
Scanty and Kneesocks could be one to Him of Powerpuff Girls.
At the end of "Sex and the Daten City", Stocking goes on YouTube. Although the site has a blatant YouTube logo, it resembles more of a cross between the former and Nico Nico Douga.
The episode could be a reference to the Powerpuff Girls episode "Town and Out" (which had the girls moving to a much more realistic city).
Also, the Art Shift has been compared to the styles of both Satoshi Kon and Studio 4C. In reality, the episode was referencing something much more obscure - Shinya Ohira's episode of The Hakkenden, which angered many fans as a result of its realistic, "ugly" aesthetics and loose style. This reaction mirrored the one that fans had while watching Osamu Kobayashi's episode of Gurren Lagann, episode 4, and this episode could easily be seen as an attempt to create a similar reaction.
The beginning of the episode features a Buddha-like Omi doll.
One of the people in the "loser class" in "Les Diaboliques" is wearing a Darth Vader helmet with cape, complete with lightsaber, but the helmet has cat ears.
The ghost that the Optimus and Megatron homages form into looks like the Fallen.
Unicron pops up at the end of the episode.
Panty and Stocking's transformed versions are each a mix of the original cartoon's and the original movie's faction leaders: Panty is a mix of Optimus Prime and Rodimus Prime, while Stocking is a mix of Megatron and Galvatron (with Animated Megatron's swords).
The dub completes the homage with soundalikes of Peter Cullen, Frank Welkerand narrator Victor Caroli.
For what it's worth, the Japanese voice cast outdoes the dub in that regard; the voices for not-Optimus and not-Megatron are actually the same voice actors as from the Japanese dub of the G1 Transformers cartoon.
Also the Starscream expy sounds kind of like its G1 self
And there's also iconic lines from the G1 movie like "one shall rise, one shall fall" and "why waste your life".
The title is a reference to George Romero's "Dead" series. This title could also be referencing the anime/manga Highschool of the Dead, the chapters/episodes of which are often titled as a main theme of the episode, plus "... of the Dead".
It's their first day as cops in Romero & Carpen Town, and the city has been overrun with zombies. Sound familiar?
The way Garterbelt uses his Shotgun is the same manner as the reverend from From Dusk Till Dawn. Also the dildo contraption Panty uses as a weapon is a direct reference to a similar weapon used by George Clooneys character in the same movie.
One of the inmates bears a striking resemblence to actor Danny Trejo, the bartender in From Dusk Till Dawn,(among other things.)
One of the convicts looks an awful lot like Francis.
At one point some of the survivors decide to throw a burning armchair into the mass of zombies to distract them, just like Ben did in the first part of the Romero's "Dead" series.
A ghost rampaging in a courthouse after ripping itself out of an electric chair? Panicky judge begging for the heroes to do the very job which he had just frowned upon? I Could swear I've seen a scene like this before...
Is "Justice always prevails" a Case Closed reference?
After her electrocution, Mrs. Wife looks suspiciously like a certain chihuahua.
Then she changes into something straight out of The Thing (1982), and when killed, her final line is, "Carpenter!"
Stocking made Panty drive her to the ice cream parlor to get the newest flavor.
Part 1 as a whole feels like a homage to Tom And Jerry and similar old style cartoons.
In Part 2, after being microwaved, Chuck reforms itself pretty much like Watchmen's Dr Manhattan after being de-atomized.
The scene where Chuck punches a fly on the wall and gets hit with a constant stream of flies is a parody of a scene from Evil Dead 2, where Ash gets sprayed in the face with a stream of blood coming from a hole in the wall.
and finally, King Crimson's In The Court Of The Crimson King with Garterbelt's screaming face
When PSG is playing beneath the Northern Lights background, Chuck is wearing Kenny's parka. Moreover when they are playing at Times Square, a billboard for UFC could be seen as well as the storefront for the now-defunct Virgin (or, rather, Virginia) Megastore.
The framing device of the rowdy punk concert closes the video in the same fashion as the music video for My Chemical Romance's cover of "Desolation Row".
Young!Garterbelt is a Captain Ersatz to Tony Montana. Hell, he even sniffed coke from a big pile on his desk before dying from a hail of bullets just like the original!
Panty and Stocking fight a six-armed clockwork suit of armor that is reminiscent of Viral's mecha.
The report the Demon Sisters give is possibly a shout out to Neon Genesis Evangelion, which had a meeting in a later episode where the Angels were all given names during a report.
Panty's plan to have sex with 1000 men before returning to heaven exceeds the goal of another anime heroine by exactly one order of magnitude.
The scene where Panty and Brief look at each other through an aquarium is an homage to Romeo + Juliet. It even features a Suspiciously Similar Song of the song used in the equivalent Romeo + Juliet scene.
The group of men Panty has sex with in the beginning look an awful lot◊ like Gary Oak.
In that very same image, the Ghosts pursuing Brief look like a bunch of demonic Totoro!
Panty's hairstyle at the party lends her a rather astonishing resemblance to Winry Rockbell.
Her entire outfit is actually a homage to an outfit Taiga wears in Toradora
The angel wings she has on also makes her more like Juliet in Romeo + Juliet.
Brief says "I'm not your doll anymore" to his father. Rei Ayanami says that to her "father" Gendo Ikari in episode 26 of Neon Genesis Evangelion.
The "ALART" that appears on Garterbelt's scanner thing is most likely a shout-out to Neon Genesis Evangelion, and not just a typo like most people assume it to be. It's changed back to "ALERT" in episode 13.
Corset's plan is to arrange a marriage between Brief and Scanty, then use Brief's penis atop a symbolically-shaped tower as the key to release an Eldritch Abomination. Sounds awful familiar, and considering the Ghostbusters shout-out with Brief mentioned above, probably not coincidental.
The emergence of the ghost resembles the opening of the gate in Fullmetal Alchemist.
Even more so when you remember that Corset is opening the gate and freeing the ghost to invade heaven, and in FMA, Father opened the planet's Gate to drag God down to Earth.
When trying to defeat the ultimate Ghost, the girls start flying around in a way similar to The Powerpuff Girls.
The words Keikaku doori are said by several characters, too many times to be a coincidence.
Garterbelt pulls a machine gun out of his afro and starts firing wildly, much like Nabeshin in some episodes of Excel Saga.
All the panties, stocking, and garterbelts Stocking orders combine to form a CG Giga Drill that literally pierces the heavens, though that was unintentional since their target was below them.
Panty and Stocking's Mom could possibly be a throwback to End Of Evangelion.
