Kurtis's design is clearly based on Cyborg 002 from Cyborg 009, as is the item "Accelerator," a set of teeth that makes you move faster (009's ability to shift into Bullet Time was activated by a switch in his mouth).
The Chinese comedy Shaolin Soccer with the Shaolin Belt. On the description of the belt it says "No, it will not make you good in soccer."
The next episode "spoiler" for Chapter 11 is one huge shoutout to Legend of Galactic Heroes. "Another page in the Netherworld's history..."
Adell himself is a big King of Fighters shoutout. He has the garb and personality (honor before reason, massive love of battle, etc) of Adelheid Berstein, the color scheme of Iori, and some of Rock Howard's moves (Vulcan Blaze derived from Neo-Deadly Rave, King of Beasts derived from Rising Tackle, Crimson Flame similar to one of Rock's charging punches).
His appearance is also heavily based on Vanessa from the same game, a redhead boxer whose clothes also look a lot like Adell's.
The version of the "Turbulence" Spear technique here looks very much like Nanoha's Starlight Breaker (specifically, the angle is the same as when the spell was used in the first season), which is reason enough to give Rozalin a spear, even if she's terrible (Rank C with Spears unless she has the Spear Technique Scroll) at using it.
The Mass Produced DESCOs in Absence of Detention each reference a Gundam Series(in order): Zeta, ZZ, Victory, Wing and After War X. Likewise, the final form of the line has the attack 'Final Boss Rondo' which emulates the scene in End of Evangelion where the mass production model EV As tear into Asuka and Unit 02.
Harpuia: The name references the leader of The Guardians. For bonus points, the weapon gives a wind resistance bonus.
Quite a few On the Next segments in the series contain thinly veiled references to the title of an actual anime or manga series. However, one of the segments decides to throw those shreds of subtlety out the window, and calls the show being previewed Sayonara, Zetsubou-Sensei.
The Catsaber's Hairball Incident magichange skill has it steamroll the targets with a giant ball of yarn that grows bigger as more and more objects get stuck to it, Katamari Damacy style.
The Ghost's Pac-ghost Chaser throws enemy into a maze filled with dots and is chased by the ghost who has now taken on the appearance of Pac-Man. The fact that it's done by a Ghost is even funnier.
I call dibs on Clyde!
The Nekomata's Boxer Kitty is a dead ringer for the Hokuto Hyakuretsu Ken, complete with a similar battle cry, the name of the attack flashing onto the screen, and the target exploding. She also uses it when you create her on those voting for the Succubus. Hell, she even references Kenshiro's famous "You Are Already Dead" line!
Their Flaring Kitty Shot magichange skill is Gouenji Shuuya's Fire Tornado from Inazuma Eleven, complete with the shot scoring a goal.
Upon creating a Slime, a cut scene will play in which the slime transforms into a hand with its pointer finger up and says "Yes, we can". The senators even acknowledge it as 'Slime Obama'!
Upon creating a Dragon, several characters will place one ballot in seven ballot boxes, each one marked with a certain number of stars. When all seven are filled, a dragon is summoned.
The Dragon's dialogue in the same scene takes the reference further, as it recites some lines that were spoken by Shen Long.
The Dragon gets a double reference with its Dragon Assassinator, first releasing a dragon of fire it uses to batter its enemy before absorbing it for a power boost like Hiei, then proceeds to punch a hole through the victim in a fashion very reminiscent of Goku's finishing strike against King Piccolo.
Disgaea 4's iteration of the 'Rising Dragon' Fist Skill is a nod to Shiryu's Rozan Shoryu Ha, more exactly, the scene where Shiryu first masters the technique, complete with a Prinny wearing the Old Master's hat at the top of the waterfall.
Even more. The Durundal is a high-mid rank sword, which is also the Infinity+1 Sword of Karin, with her ultimate skill, Sonnestark becoming the ultimate skill of the Cockatrice. Also, the true final chapter deals with a mythological area filled with Malice, being used by someone close to the cast. Much like the final part of From The New World.
In the closing cutscene for episode 3, (at around 12:25 in the video linked), one of the pictures is a reference to the ending fight scene of Busou Renkin... complete with Fuka and Valvatorez holding sardine swords and spearing a shark-esque guy.
The consumable Pizza item is a double reference: Eaten by turtle and cat martial artists alike.
The Reaper's Circle of Death attack has this description: The only thing it's missing is a catchy song
Sicily's last move, Sicily Delivery, goes like this; First she stuffs her enemies in a box, then she flies the box to the Antarctic, then she smashes the box with a Hammer. There are a few differences but this attack is essentially Yzma's original evil plan
The scene in which the cast confronts Artina for kidnapping Porkmeister is played out like a typical cop story with Flonne yelling over the microphone for the suspect to turn herself in and Laharl barking orders like a commissioner.