Psychic Squad (TV)

in ep. 9, at around 4:12, hayate and nagi from hayate no gotoku! can be spotted. also, babo, ginta, and dorothy from MAR can be spotted in the background

At the beginning of episode 09, the infamous curse scene from The Ring was shown, which scared the life of of the Children

In ep 11, at about 3:47, you can see that the Sanzenin Family is also booked in on the Welcome board, likely a cameo appearance.

There is indirect reference to multiple anime in first episode. Right in the beginning in the store where Muscle Ōkamais hiding you can see posters such as EARTH or WITCHSWORD ... which are references to AIR and Witchblade.

Episode 27 three different crossover cameos appearing in the episode. Perrine, Sanya and Eila of Strike Witches all appear in the classroom, the girls of Lucky Star also appear in another background (with brown hair no less), and Ranka Lee from Macross Fontier appears illustrated in her “Kira” pose.

In ep 13, the trailer for the film at 4:40 is a play on the anime Ghost Sweeper Mikami. Akashi Akie has the same eyelashes, dress, earrings, necklace and spiritual weapon as Mikami, and ended the trailer by repeating Mikami's favourite phrase of money being everything in the world.

Patty Crew's name is a pun off of the word "particle" in Japanese. This is because her power as an Esper is to control particles.

In episode 9, the toy that Kaoru wishes to buy is labeled a "Hahiru" set. Given the bunny outfit, the yellow headband, and the school uniform, it's clearly a reference to Haruhi. Given Kaoru's voice actress...shout-out.

In episode 9, the ESPer at the quarry stated that he "always wanted to be at a climax." This is a reference to Momotaros' catchphrase from Kamen Rider Den-O.

When Minamoto drops his satchel in episode 10 a number of what are clearly Zettai Karen ADR scripts fall out.

in episode 10 while boarding the "Babel 2" (a special submarine) there's a BGM playing, making the scene resemble the depart of the supporting squads (like G.U.T.S.) in the "ultramen" series

In episode 15 at minute 21:30 the mobile phone retrieved from the river resembles a Nokia 6280/6288.

In episode 18, Hayate and Tama of Hayate no Gotoku! and Ink and Sumi of Moetan made a brief appearance in the busy background

In episode 18, the moment you have seen Tama and Ayasaki Hayate from hayata no gotoku! You will also notice Kasumi Aika and Katsura Hinagiku from the same series walking by.

In episode 18, at the same point you see Hayate and Tama, you see Nabeshin from Excel Saga in the lower right.

Later on in episode 18, you can find Ayumu Nishizawa from Hayate no Gotoku in the scene with Aoi and the "gang members."

And following that scene in episode 18 is a blatantly obvious reference to Star Wars, courtesy of "the Queen."

In episode 19, you can see a billboard for SOS Burger. Given the Haruhi reference from an earlier episode, it's possibly a reference to the SOS Brigade.

In episode 21, Nabeshin can be seen again watching the crime involving the pig. In fact, Nabeshin makes more random appearances all through the anime.

In episode 26, at around 1:16, Hayate is seen with Nagi from Hayate no Gotoku.

The mock-brainwashing scene in Episode 29 is an obvious parody of the first Kamen Rider TV series, made more apparent by the presence of the Typhoon Belt.

In episode 30, the phone that Fujiko has that detected Hyoubu is clearly an iPhone, even having service from AT&T.

In episode 37, the beginning can appear to carry a tone relative to something in Code Geass. This becomes clear when Hyobu does the infamous gesture Lelouch uses before he uses the geass on someone.

In episode 49, Midori from Midori Days can be seen hooked on to Sakaki's cell phone.