One of the late scenes in the opening, where Alexis Kherib opens his hand to fire on Gridman (who flips to evade the blast) is either a Tekkaman Blade reference or one for the Gaiking LOD second opening (comparison video here).
Sho Utsumi frequently references how things should/would play out if the kaiju attacks were happening in an Ultra Series. This is of course a call out to Gridman being a Tsubaraya series that's essentially an Ultraman in everything but name.
In a move which has surprised fans on both sides of the Pacific, SSSS.GRIDMAN is FULL of Transformers and Go-Bots references. Many of the people working at Studio Trigger are long time Transformers fans who have contributed to the franchise both officially and unoffically, and references have popped up in a number of Gainax and Studio Trigger series. But those were blink and you'll miss it affairs (e.g. a Gunman in a Gurren Lagann crowd scene is shaped like a Decepticon symbol). In Gridman if you're a character with any kind of distinct visual style, you're probably a Transformers reference. Not only that but the references are dominated by call-outs to Shattered Glass, an obscure piece of long-running convention fiction which created a mirror universe of good Decepticons and evil Autobots. Other references include the aforementioned Go-Bots, the Movieverse, and even the toy production companies.
Yuta takes design cues from Classics Cliffjumper, the universe hopping POV character from the first comic — His hair is styled into horns, his shoes are inspired after his toy's front bumper and his backpack is designed after the toy's jetski addon.
Utsumi takes design cues from Shattered Glass Sideswipe — His shirt has the same color scheme as the toy. The '8' on his shirt has the same slash as the toy's Autobot brand, and his backpack has TURBO on it, just like the toy. He also carries a pair of yellow binoculars that look just like Longview's transformed state.
Akane takes design cues from Shattered Glass Optimus Prime — Her color scheme is just like the toy's, the right lens on her glasses are shattered in the same way as the toy's right windshield and her headphones are closely modeled after the toy's head antennae. Even her chest is a reference, mirroring Optimus' own top-heaviness in the truck portions that make up his chest. Her real self wears white, much like Shattered Glass Optimus Prime once he was revived as Nova Prime.
Rikka takes her cues from Shattered Glass Megatron — her colour scheme and clothes markings corresponding with the toys layout and her backpack resembles the toy's rumbler tank accessory.
Anti takes his cues from Shattered Glass Rodimus — color scheme and clothes designs corresponding to the toy's layout. He also uses a buzzsaw, which Rodimus had in place of a hand as a punishment. Anti also has a mutilated body part, though it is his eye, as opposed to Rodimus's hand.
Rikka's friends take their cues from Shattered Glass Starscream and Soundwave — color schemes and designs, like Namiko's hairclip (a Cyber Planet Key) and tie are based on the toy and its accessories, and Hass has a white facemask and "Ravage" printed on the blanket she always carries around.
Appearing more prominently later on, Rikka's other two friends, Ramo Marusa and Ako Furuma, take their cues from Shattered Glass Astrotrain and Thundercracker
Rikka's mom's apron has G1 Megatron's torso printed on it and has a colour scheme matching a specific toy reissue. Additionally, the eye-like single earring she wears implies she's based on Rewind, given her business of collecting and passing on old junk or, given they are in cyberspace, old data.
Yuta's classmates include call outs to Shattered Glass Straxus, Octopunch, and Treadshot as well as Go-Bot leader Cy-Kill.
Samurai Calibur and the other three Assist Weapons are inspired by the Dinobots from Transformers: Age of Extinction, particularly Slug, Grimlock, Scorn, and Strafe — with the patterns on their collars matching molded details from their toys.
Additionally, the Assist Weapons and their attacks are named after the Samuraized Attack Vehicles from Superhuman Samurai Syber-Squad and their controllers (Tank, Syd, Amp, and Lucky), with Samurai Calibur being named after the show itself ("Superhuman Samurai").
The series' first victim, Sakiru Tonkawa, meanwhile, is a homage to Cy-Kill from Challenge of the GoBots, right down to her name referencing both Cy-Kill's and Tonka, the company that created the Go-Bots. Her role in the story, meanwhile, is an allusion to Cy-Kill's recurring role as an "easter egg" who gets killed off in various Transformers stories.
The four-man college group Arcadia in Episode 4 is comprised of various versions of Jetfire: Shattered Glass, Generation 1, Generation 2, and Animated.
Though primarily based on her predecessor, Anosillus, the young girl from Episode 6 has a green-and-brown color scheme not dissimilar to Shattered Glass Primus himself.
Other characters are also named after toy companies: Kena stands for Kenner, Hass stands for Hasbro, Namiko is Bandai Namco, Toiko is ToyCo, Takara is Takara Tomy, and Doi Hako is ToyBox.
The way Gridman charges at the kaiju with the truster on his back to cut him up with Gridman Calibur is visually similar to the same way that Ryuko from Kill la Kill uses the thruster on the back of her outfit to slide-charge then slice enemies with her sword. More specifically, it is visually similar to the way Ryuko defeats Nonon.
Max Gridman and Anti's punching scene replicates the memetic punching scene of Masami Obari.
At one point while seeing the inside of Akane's trash-filled room, the display cases are filled with clay models... Including many Heroes of the Storm characters, including Pajamathur, The Butcherlisk, and Zagara.
While the Gridman Alliance and Neon Genesis Junior High are peeping on Rikka and Akane, they hide in a pastry shop that played the ending theme song of Ultraman R/B, "Yume Hiko". Since the singer is Suzuko Mimori and her character Namiko is in this episode, it helps.
One of the donuts resembles Hellfire Boy of ''Inferno Cop''. Speaking of Inferno Cop, the video playing on the karaoke bar's screen is the karaoke version of Die Hollen Polezei.
The back of Yuta's phone case has an Autobot-symbol-shaped hole for the phone's brand logo.
The boys of Arcadia are based on the real-life Youtuber group Toukai On Air. Their group name as well as their individual names are taken from toy companies that produce Macross figures. Doubling down on them, each one is designed after an alternate version of the Transformer Jetfire (Generations 1 and 2, Animated and of course Shattered Glass), whose original figure was an imported Super Valkyrie figure from Macross.
Wooser made his cameo appearance in Yamato's video.
Since former Kaiju designer of Ultra Series, Hiroshi Maruyama returns, this episode's monster resembles a cross between Twin Tail, Litomalus and Pedoleon.
Its modus operandi pretty much resembles that of Kutuura.
As Gridman stands up next to the building where Rikka and Calibur are standing, it's a direct call out to a similar scene in ''Metal Armor Dragonar".
Anti, Max and Calibur all wield weapons modelled after those used by their transformers counterparts (Rodimus' saw, Grimlock's mace and Slug's swords).
Additionally, Borr's dagger is modelled after Skorn's swords, and Vit's weapon is modelled after a sword that Slug uses. They're only shown in the opening, however.
The magazine Sho is reading is the real life Uchusen, a trimonthly hobby magazine which features information on tokusatsu shows. The front cover features Hunter Knight Tsurugi, Techtor Gear Zero and Andro Melos, which makes it doubly funny if you know the background of this anime's production.note Akira Amemiya first approached Tsuburaya and proposed to them to make an Ultraman anime. Tsuburaya told him Ultraman characters are basically off-limits, but he can use Gridman and Andro Melos. Guess which one he chose.
The back cover in fact has pictures of OxT and Maaya Uchida, both of which sing the opening and ending themes of this anime respectively.
The music store is playing a piano version of "Die Hollen Polizei", the ending theme to Inferno Cop.
The kaiju-girl that Yuuta meets is inspired heavily by Anosilus, a kaiju from the original Gridman series. The symbol on her shirt is worn by a character in the same episode as her original debut. Also, her namesake was noted for being a peaceful kaiju that, much like how the new Anosilus hadn't been made by Akane, wasn't made by Gridman's Takeshi Todo.
When Anosilus and Yuuta speak, a piano rendition of "Yume no Hero" (the original Gridman OP, known colloquially as "Baby Dan Dan") plays.
The store Utsumi and Akane meet in is monitored by a Cat's Eye-brand security camera. While it may seem like a nod to the anime/manga Cat's Eye, it's actually a throwback to the security company featured in Episode 12 of Gridman.
The green, blocky pattern on the sky-ceiling is the same design as the ceiling design in the original Gridman/Syber-Squad's digital world.
Full-powered Gridman's punch is a reference to Tekkaman Blade slugging his evil brother in the face (Comparison videohere).
Also something of note while on the topic of references - the "Man" in Mandarake? In the original series, Ultraman was often addressed as just "Man".
Utsumi wrote God's in his heaven, All's right with the worldnote an excerpt of the Pippa Passes by Robert Browning, the slogan of NERV, in English on a piece of paper while studying for exams.
Akane's stabbing of Yuta is framed exactly like the scene in Transformers: Shattered Glass when SG!Optimus kills SG!Hot Rod in exactly the same fashion.
When the crew stands around in the hospital, a nurse can be heard calling for a "Yuichirou Kanesue". That's a character from Kinpachi-sensei, whose actor went on to play Koji Doigaki, a major character from Ultraman Cosmos.