Yurin is a homage to Lalah Sune, while Emily is Frau Bow.
Gundam AGE-1 looks similar to the RX-78-2 Gundam with its shield looking similar to the Gundam MK II .
The Genoace MS is an expy of the GM.
The AGE-1 stabs its first victim in the fashion of RX-78-2 stabbing a Zaku up close with its beam saber, except AGE-1 stabs the UE a few more times before letting it fall to the ground.
The AGE System gathers data from the battles that it fights in in order to evolve and become stronger. Not very unlike the RX-78-2's learning computer...
G-Exes is clearly a name made after Gundam in the same fashion as G-Saviour; its appearance is more like Nu Gundam than the Genoace Custom, too. It also has some resemblance to G-3 Gundam.
The way Desil fires the Gundam AGE-1's beam rifle under the arm is a direct shout out to Amuro.
The motivations for the UE, aka Vagan, fighting against Earth Federation resemble that of the Principality of Zeon.
Episode 29 shows us the return of the Core Fighter.
The history of warfare between the two factions in Fardain is strikingly similar to the timeline.
The first-generation episode "Space Fortress Ambat" is near the end, just like "Space Fortress A Baoa Qu".
Similarly, the third-generation follows suit with "Space Fortress La Gramis".
Geera Zoi calls the Diva a Trojan Horse after seeing it transform into a White Base lookalike.
Zalam's Space Suits bare more than a passing resemblance to the Zaku Mobile Suit.
Don Boyage distinguished himself from his underlings by having his space suit look like a Gouf.
Both the Federation Forces, Zalam and Eubas battleships bear striking similarity to the Salamis-class cruisers from Universal Century. The UE's battleships, however, are basically slightly revamped Musai-class cruisers, also from UC.
Beyond his similarities to Amuro Ray, Woolf's nickname of White Wolf can also be a reference to Zeon ace Shin Matsunaga.
The Gundam Age-2 has three times more thrust in G-Strider form than in mobile suit form.
The Zeydra, a red mobile suit, is three times faster than other Vagan suits and piloted by a guy wearing a mask. Also, it apparently has the ability to unleash a super-powered version of Char's infamous kick.
Like Zeon, the Vagan are in control of a good deal of Earth during the third arc. And their assault on the Federation stronghold was beaten off.
The trio of enemy pilots in Episode 31 may be a reference to the Black Tri-Stars.
Towards the end of Episode 33, the shot of birds flying over Rostroulan is a definite nod to the birds in flight while the White Base leaves Jaburo in the original series (oof).
Captain Ash seems to have adopted Char's (and Rau's) tendency to sortie without a flight suit. He also implements the Char Kick in his fight against Kio.
Fram's premonition of Zeheart's death in episode 41 resembles Lalah's.
Farsia is a mind-controlled equivalent of Elmeth, and Defurse is the UE's Big Zam.
During the Third Generation, the Diva carries three children on it, much like Katz, Letz, and Kikka. And Wendy is assigned to take care of them, making her the Fraw Bow.
The Phantom 3 are expies of the Black Tri-Stars. They even have their own equivalent of the Jet Stream Attack.
We're even given an expy for a place. Roustroulan, the Federation's HQ on Earth, is one to Jaburo, down to the location.
It is even infiltrated by the enemy in the same manner as Jaburo, via underwater mobile suits with a red lead unit.
Woolf and Flit's mock battle to decide the pilot of the Gundam is a shout out to Kou Uraki and Bernard Monsha's mock battle for the right to pilot the GP-01.
The ending of the first season ( the protagonist fails in his mission and becomes highly embittered, the captain is punished unjustly) is pretty much how Stardust Memory ended too. Thankfully, the series wrapped up better.
While the Diva pilot crew are eating lunch in episode 20, it pauses for a second on Asemu's fork simply stabbed into a carrot, a subtle nod to Kou Uraki.
More than that, it's been stated that the relationship between Asemu, Romary, and Zeheart is meant to parallel that between Kou, Nina, and Gato.
Furthermore, Asemu Asuno is not unlike Kou Uraki for all the low self-worth in him at the young age. And, for all the initial Fa Yuiry likeness, Romary Stone behaves much more like Nina Purpleton. Woolf as of the 2nd Gen is Bernard Monsha, with none of the asshole characteristics.
Zeheart is not beyond giving motivational speeches to the Vagan army live and/or via projected space holograms, which is basically how Char Aznable did it as the Second Neo Zeon movement leader.
The Vagan are not above manually pushing ships while using Mobile Suits. Ironically, while in Mobile Suit Gundam: Char's Counterattack the Mobile Suits are pushing Axis away from Earth, here it's practically in reverse.
In the final episode, both the Vagan and Federation work together to avert the destruction of Second Moon, similar to how both Zeon and Federation suits teamed up to prevent Axis from crashing into the Earth.
The AGE-FX Gundam is parallel to the Nu Gundam, and is even able to use its C-Funnels to form an impenetrable energy shield around itself, much like the Nu Gundam and its Fin Funnels. The Gundam Legilis later displays a similar ability with its bits.
The Genoace Custom's shield has a red wolf-head painted on it, strongly resembling the red unicorn-head on Nu Gundam's shield. Their pilots' nicknames are also similar (The Federation's White Wolf and the Federation's White Devil, respectively).
The destruction of the weapons by both Euba and Zalam before the story begins, which was supposed to bring a permanent peace to humanity, is a reflection to the ending of Mobile Suit Gundam Wing Endless Waltz.
Asemu tries on a Vagan helmet that gives him X-Rounder abilities, but at a costly price, just like the Zero system.
Flit tries one of the Wing Zero's infamous maneuvers with the AGE-1 Glansa (spreading his arms and firing the Dual BFG in two opposite directions), minus the spinning part.
Yurin giving directions to Flit in Episode 2 is similar to Tiffa doing the same for Garrod.
In a flashback before she dies, Yurin is shown with her hair down, parallel to Tiffa with her untied hair when she was possessed by Lucille Rilliant, emphasizing further the two Shrinking Violet's similarities.
Like Yurin, Fram is also shown with her loose hair as she speaks to Zeheart in a vision before she dies, also parallel to the same Gundam X scene above.
In episode 12; in order to capture the Diva undamaged, Stoller Guavaran fired off flash bangs and sent in mobile suits to target the bridge and Mobile suit Launching bays. This was the same tactic that Garrod Ran used in the first episode of Gundam X, of course he couldn't use it to the same effect.
The Galette brothers' mobile suits in the second season have similar color schemes to the Frost brothers'. Also the fact that they're a Sibling Team, though the Galette weren't affectionate to each other unlike the Frosts.
What Zeheart says to Asemu after their fight in Episode 20 resembles Carris Nautlius' "The Reason You Suck" Speech to Garrod after their first fight.
The first combined SigMaxiss Cannon shot was similar to Garrod's first Satellite Cannon shot.
The EXA-DB is said to contain mobile suits which could remotely control others not unlike the Gundam X and its G-Bits.
The Zedas and Khronos mobile suits could remote-control friendly suits, even taking control away from their actual pilots.
Lu Anon is skilled in illustration especially in drawing landscapes, a talent Tiffa Adill also possess.