Expy in this series.
- The wardens and other security forces are clearly a shout-out to Ultraman and Sentai series. Word of God explicitly compares Kang to Ultraman and Gupta to Ultraseven.
- The wardens and security forces at the female's prison are a Combining Mecha that references either Voltron or Power Rangers.
- The officers of Science Police Team G.R.E.A.T., who seek out and subdue criminal Kaiju, wear uniforms (complete with helmets) that make them somewhat resemble Science Ninja Team Gatchaman, with a Palette Swap and minus the capes. One officer, who witnesses the death of Chisato's partner, courtesy of the Black Humongo, is an expy of Jinpei.
- The Giant Mecha piloted by Nobuko Matsumoto resembles a female take on Gigantor, wearing a kimono.
- The Humongo brothers—Green, Red, Blue, Yellow, and so on, but especially Green and Red—are expies of Sanda and Gaira, coupled with muddled origins. Red insists he isn't a sea lizard like his brother Green; he was a boy exposed to radiation while living in the wilderness, while Green insists he is not a Frankenstein.
- The Kaiju that killed Jeong's parents is an expy of the title monster from Pulgasari, but with the head of Kim Jong-Il.
- The Queen Bee, a female bee kaiju, is an obvious homage to Mothra — especially since she is attended to by a pair of singing fairies and the female prison used to be called Rebirth Island.
- Mechazon is a stand-in for Mechagodzilla, being a robot built to destroy the organic monster he was modeled after. He develops a mind of his own and refuses to fight, similar to the "Kiryu" Mechagodzilla model from Godzilla Against Mechagodzilla.
- Whoofy is essentially a twisted, tormented copy of Minilla, Godzilla's son. He even (sort of) has a human best friend, like Minilla had in All Monsters Attack.
- Monster X-Zero is a three-headed, winged dragon, just like King Ghidorah. He is missing two of his heads, alluding to Ghidorah's history of getting decapitated, and his name is a combo of Monster Zero, Ghidorah's codename from Invasion of Astro-Monster and Monster X, the name of his humanoid form in Godzilla: Final Wars.
- Victoria Von Vilestra, leader of the Seijin Gang, has minions made from clay, and used to look down on Earth from the moon with a telescope like Rita Repulsa / Bandora. She dressed quite a bit like her, too.
- The boss of the Maketo gang (the ones behind the Human Pitfighting tournament) is a giant green Pikachu look-alike. To drive the point home, he's called Pikadon.
- Team V.I.T.A.L.I.T.Y visually resemble the Dinobots.
- Sprinkles, a prisoner introduced in season five, resembles a giant unicorn, claims to come from a magical land far removed from earthly concerns, and helps children solve their problems via magic, not unlike a certain dragon of song and cartoon.
- To push the Pokémon parallel further, Pikadon's legal defense team consists of two human-like lawyers with colorful hair and a flair for the theatrical, and their smallish Kaiju assistant with a Verbal Tic.
- Zugaigo is an expy of Gamera, being another shelled kaiju beloved by children. More specifically, he's a reference to Gamera's characterization in his first outing and serves as a deconstruction of the Friend to All Children moniker the monster received in a movie where, in spite of saving a single child from falling to his death, he still destroyed Tokyo and killed thousands.
- Season five introduces the Enigmirians, Human Aliens who are expies of the Human Aliens who have appeared in Invasion of Astro-Monster and The Mysterians.
]* Sleve
McDichael, Pikadon's alleged murder victim, calls on his
Mons to help him in his fight with Pikadon. They are
expies of Pokemon, including Snorlax.
- The Hermanculoid is an unlikely expy of Mothra, complete with a tribe of humans who worship the giant hermit crab as a god and live inside his shell.
- An expy of Lakitu, cloud and all, interviews Electrogor after the Alien Invasion has been thwarted.
