Screwed by the Network: Getting moved from Friday nights to Wednesday nights then finally moved practically unannounced to an early Saturday morning slot all in the first season alone is never a good sign.
The Galatic Guardians are one big one to 70's anime superheroes and tokusatsu like Science Ninja Team Gatchaman and Kamen Rider (albeit more as the bad guy organizations than anything).
The opening of the Rift Gate looks strangely like one of the later openings for Toonami.
Episode 8 bares a number of similarities to Harry Potter. Orphaned youth with chip on his shoulders; check. Blonde haired perfectionist with two hench-friends who antagonize the boy; check.
It seemed more Ender's Game (anti-gravity combat training).
Baron's aristocratic name, long nose, and hairstyle marks him as a younger counterpart to Osamu Tezuka's character Duke Red.
Episode 8 also had short plump young boy with red hair and big eyeglasses. Hmmm...
The farm in Tashy 497 is the exact same one from Courage the Cowardly Dog. All that was missing was an old lady yelling at her grumpy husband because of the house blowing up and the man blaming it on a pink poodle.
The Titan resembles a semitransparent version of Gigantor.
Galaluna and the Mutraddi beasts recalls similar concepts from Voltron.
The organization designed to protect Earth from alien invasion is called GGG.
G3's standard soldiers' outfits look a lot like those worn by Red Impulse, although the helmets are reminiscent of Bioman's.
Right before he stretches out his nose, Octus' shifting disguise in episode 11 looks suspiciously like Nick Cave.
Those G3 bipedal mechs that appeared near the end of episode 11 bear a striking resemblance to Zentraedi battlepods.
The guy who beats the crap out of Lance looks oddly like the blue Guardian dude from that one episode of Samurai Jack. Even as far as also being voiced by Kevin Michael Richardson.
A boy named Jason who looks and acts a lot like Cody flirts with Illana in "The Ballad Of Scary Mary".
Scary Mary's last name is Cavanaugh, a reference to Christine Cavanaugh, the original voice of Dexter, who retired from voice-acting in the early 2000s and became very reclusive ever since. Scary Mary's appearance seems a visual shout out to Velma Dinkley.
Hobbes from Escape from Galaluna looks quite a bit like Race Bannon, don'tcha think?
The Mutradi invasion fleet seems to be made out of Planet Crackers
Kristin, the goth girl, looks like an older version of The Big-Eyed Girl.
Newton holding the boombox over his head (albeit playing ads) is a shout out to the romantic gesture from Say Anything.
In the episode "A Family Crisis" the G3 space station looks like it was built to reactivate a dying sun
In the episode "A New Beginning" General Steel in in what he calls "THE HAMMER!" and proceeds to beat up a monster while saying "Can't touch this." Not to mention the re-purposed Star Wars lines mentioned around G3's airborne base. Then there was the launch sequence of G3's Colonial Viper-like fighters, which resembled the Viper launch sequences from the new Galactica series.
In "The Demon Within," Ilana mentions that the only one of her arranged dates on Galaluna she was actually interested in was "Prince Simon of Duran," a reference to Simon LeBon.
During the series finale, after the HMER gets wrecked, Steel blasts away at the enemy with an assault rifle in a manner very reminiscent of Dozle Zabi in Mobile Suit Gundam. He's lucky enough to not meet quite the same fate, though.
