The opening credits features cuts and sequences that are done to formula commonly seen in mecha works done by Sunrise and Masami Obari.
The Principal Robot run across the scene with its comrades in some type of transportation mecha—Most notably in The Brave Express Might Gaine style with Gaine running on foot, and Might piloting his plane.
Final scene with all the cast—General Brave Series style. Most notably in GaoGaiGar style due to the work's Real Robot cast and setting.
Bravern's design evokes Exkaiser the most in terms of design and color scheme.
Bravern's communication device being on his wrist and shape of it it bears a resemblance to Sworgrader's Alpha Axe, even down to the impact shot on Superbia being identical to when Swordgrader used Alpha Axe on the Geisters.
Bravern keeps on killing Cupiridas as he keeps respawing much like how Genesic GaoGaiGar repeatedly destroys Palparepa in their penultimate battle in GaoGaiGar FINAL. On top of this, Cupiridas says GaGaGaGaGa, much like the intro/mid song lyrics for GaoGaiGar's opening.
Bravern being impaled by Ira and dying(?) gives major GaoGaiGar FINAL vibes were all the Braves are dealt a serious blow from sneak attack, especially Tenryujin who was impaled by Purunus. Made even worse by the fact that before King of Kings: GaoGaiGar vs. Betterman the fate of the 3G Braves were left unknown apart from Genesic Gaogaigar, with the last shot of them being severely damaged and on deaths door.
To add to this, Bravern just before dying shows his optical camera begin to flicker and short out before going black, much like how Mic Sounders optical display screen did in the final episode of GaoGaiGar. The difference being, we see Bravern's optics go out from his perspective, were as Mic's was shown from an outsiders perspective.
The finale ends with Isami, and Lulu nude from being ejected from Bravern and Superbia, and reunited with Smith back to human flesh is reminiscent to the finale of GaoGaiGar of Mikoto and Gai's heartfelt reunion after gaining back both of their human flesh from their final confrontation.
When using his "Brave the Summons," Bravern has fins emerge from the side of his shoulders, almost like the Gundam F91. It may be a multilayered Actor Allusion reference, since Bravern shares a voice actor with Shinn Asuka, whose Destiny Gundam's afterimages are themselves a nod to F91.
Additionally, there's a shot that bears a resemblance to 0 Gundam's first appearance in Mobile Suit Gundam 00, where it floats in the air while shot from below. It may also be a nod to 00 Raiser's Trans-Am Burst.
Isami being The Stoic Japanese soldier with Hot-Blooded moments that make him Not So Stoic, who pilots a red mecha, and Smith being an eccentric American Blonde who has a relationship with a blue haired, red eyed alien girl seems to be a callback to Kyosuke Nanbu and Excellen Browning of Super Robot Wars. It also helps that Obari has worked on Super Robot Wars OG The Inspector as a director, which primarily focuses on the latter as the main characters.
Bravern's full Japanese title has Bakuhatsu/Explosive in it and Bravern has a tendency to name his attacks in outlandish, over the top ways. Coupled with how Burn Blade's Blaze Up generates a beam sword on a traditional sword hilt, it resembles Ryusei saying Bakusai/Bursting when using the SRX's finisher slash.
Ep. 5 introduced Cupiridas, who is voiced by Tetsu Inada, who also voiced Rätsel Feinschmecker. His color scheme even has the classic black-and-red Trombe color scheme Rätsel's mechs sport. To add to this, he bears a striking resemblance to many of the Balmarian mecha, albeit more detailed and stocky.
In the final episode, when Isami grabs Superbia's sword form, he says "Let's go, my friend!" in the same tone and style that Rätsel does when fighting alongside Sanger.
Elements from Obari's works:
The green shape on Bravern's cockpit and forehead looks a lot like a Tek Setter, from a show Masami Obari also worked on.
Bravern enhances it's Burn Blade by saying BlazeUp complete with the Obari Pose/Brave Perspective. Both Gravion and Bang Bravern are directed by Obari.
Superbia is shown leaping on top of a building and landing with both feet together as the camera pans up to show him, much like how Bloody II did in Dangaioh.
At the end of episode 7, as ominous clouds begin to roll in, Bravern utters "A storm is coming." This line*dubbed into English as "Feel the storm... it's coming." was spoken by Terry Bogard in Fatal Fury:The Motion Picture, which was directed by Obari.
Burn Bravern's colors are the inverse of Sol Gravion, with the design being very similar. Not only has Obari worked on it, Kenichi Suzumura has a major role as Eiji Shigure.
Elements from other works:
In Episode 3, Bravern has to prepare for deep sea combat by flooding his own cockpit with highly oxygenated water that Isami can somehow breathe in. Bravern even directly mentions The Abyss.
When Lewis tries to tell Lulu that she can't use the new TS given to him, she's shown decked out with grenades, a Carl Gustav RR, an M60E3 GPMG and a recurve bow with camo face paint and red headband, chaneling John Rambo.
Bravern and Lulu’s message to Superbia regarding “to copilot, is not to abuse the other partner, but to understand and become one body in heart and spirit,” as well as the sequence of Lulu’s full control of Superbia complete with her equipping her battle suit along with wings spread out as her main cockpit design is one big reference from B't X; of which includes the reference of Teppei and Bt’X’s “Battle Gear: ON!” Transformation Sequence in a Magical Girl Warrior twist.
The final shot of Episode 4 with Isami and Bravern at the front of the aircraft carrier together is one to the ending of Transformers: Revenge of The Fallen, with Sam and Optimus Prime in similar positions.
Bravern uses an arm taser like attack to shock Superbia. The twin forked design and the electric current running through looks very similar Fafner's Ruga Lance.
The wave used to redirect and control the naval missile salvo seems very similar to both Mark Sein's Wave in Ep. 9 of Fafner Exodus that saved every Fafner from the Festum. It also happens that Bravern's Ruga Lance like device above happens afterwards.
It also bears an uncanny resemblance and function to Cure Felice's wave used to redirect enemy projectiles. Even the circular look to the wave and the way both Bravern and Felice hold their arm out to the side is almost identical. Not to mention the pose Bravern makes beforehand emitting the wave is like Hachans when she emits a wave to defeat Dokurokushe.
In Episode 12, Isami makes the iconic Ultraman rising pose when Bravern grows.
bear a similar look and function to the Voiture Lumiere used by the Destiny Gundam