Tons and tons of shout-outs here — Neon Genesis Evangelion, Fist of the North Star, Macross, Star Wars, Urusei Yatsura, etc. Basically if there's any anime series or movie you remember fondly, there's a good chance of a reference.
- Evangelion references are constant enough that it got author Yoshizaki brought to Gainax to design official merchandising for them in 2005, the Moe Anthropomorphism-themed Angel XX line.
- Lampshaded at least once — the chamber collecting March Zone Energy creates a manifestation of Rei Ayanami who claims to be "the fourth one" and starts talking about "March Impact". The reference goes clear over Fuyuki's head.
- More than once: in the episode that introduces Kogoro, he and the frogs disappear into another dimension in the middle of a pastiche of Space Sheriff Gavan, and when Natsumi asks "What the heck was that?", Fuyuki replies, "I think it was a parody of some old kids' show."
- The Narrator in the English version repeatedly urges the audience to go track down episodes of Space Sheriff Gavan on Youtube, saying it's a really cool show.
- Not to mention that there are two seperate episodes lampooning Kamen Rider Den-O and Kamen Rider Double.
- Evangelion is not the only Gainax anime referenced — Angol Mois looks just and even behaves a bit like Lt. Kitsurubami from FLCL.
- Especially notable for a Japanese anime is the number of Western shows that get a Shout-Out. Star Wars may be an obligatory one, but there are more recent ones for Cloverfield, Tim Kring's Heroes, and one chapter of Musha Kero has a sedan chair rigged to explode if its speed drops below a brisk run.
- Nevula (Alisa's "Daddy") appears to be something between a Parasyte and Venom.
- Sarge has shown the curious ability to turn into The Incredible Hulk when sufficiently angry!
- The dub gets in on this as well, referring to Battlestar Galactica, Robotech and a bunch of other stuff targeted toward U.S. viewers.
- And also features not one, but two instances of "Get to da choppa!"
- Dasonu* Maso strikes the classic pose from the original Saturday Night Fever poster and has a Cyclops visor.
- And in the same episode (in the dub), after getting an afro, Dororo complains that "Afros are for Samurai, not ninjas!"
- In the episode where the Hinata family visit the grandma, at the very beginning, two people are driving... Hilariously, they're Palette Swaps of Lupin and Jigen.
- The entirety of the episode "Jerseyman Fuyuki" is a somewhat affectionate Take That! towards the notoriously bad 1974 anime Chargeman Ken!. Fuyuki buys Ken's jersey online and becomes Ax-Crazy after putting it on, alluding to how Ken constantly does needlessly cruel things in the name of defeating the Juralians and gets no comeuppance for it.
- The dub's version of the Lotus-Eater Machine Tamama uses on Sarge in episode 3 is called the Purple Mercy Lotus Eating Lotus.
- The size-changing Flash Spoon is a shout out to an episode of the original Ultraman where Hayata accidentally attempted to transform into the giant hero with a spoon rather than the Beta Capsule. Its name is a shoutout to a Doraemon flashlight with the same function. In the dub, it's called SpoonWOW and Sarge mistakes it for a dinglehopper.
- Another Ultraman reference occurs in episode 151b when Natsumi, Keroro and Giroro face a giant Chupacabra with a frill added on named Capras — a parody of the infamous Ultraman kaiju Jirass
(well known for being just Godzilla with a frill added on). And then Capras' frill gets torn off by an enlarged Giroro, mimicking what Ultraman did to Jirass.
- Another Ultraman reference occurs in episode 151b when Natsumi, Keroro and Giroro face a giant Chupacabra with a frill added on named Capras — a parody of the infamous Ultraman kaiju Jirass
- The dub also has Keroro claim he's not a robotic cat from the future sent by Fuyuki's great grandson to make his life easier. For context, he meant something like "What am I, Superman?"
- There's actually a very similar line in the original, when Fuyuki asks Keroro to make it rain and ruin the sports festival, he receives a similar reply. Later, it's a desperate Keroro who receives that answer while bothering Kururu.
- When empowered by extreme humidity in episode 4b, Keroro puts on a yellow shirt just so he can tear it off a la Hulk Hogan.
- Keroro's father takes a train into space to leave Earth for Keron.
- In the English dub for "Wet, Hot, Beach," a side effect of Kululu's aging ray that makes Natsumi look like an adult is that she keeps dropping slang and references to American pop culture from the 1920s and 1930s, much to her frustration.
- At the start of episode 7b, Keroro and Mois are watching an obvious parody of Denjin Zaborger with Yutaka voiced by Nobuyuki Hiyama just to make the parody even more awesome.
- In episode 166, Natsumi spends the rest of the episode wearing a Zaborger suit.
- The Hinata Family enters "Forbidden Battle Mode" in Sergeant Keroro Season 3 Episode 142 Part A, which transforms their suburban home into a cross between Camp Big Falcon from Anime/Voltes V and the White Base of Mobile Suit Gundam.
