When May changes the capital "I" in "BUILD DIVERS" to a small "i" and declares it "a different name", first-time viewers might think it's a throwaway gag. It is, kind of, but it's also hinting at (season 1 spoiler) her identity, since making a distinction between uppercase and lowercase versions of the same words is a hallmark of computer languages.
Why does May go completely out of character when hailing a taxi? She probably learned from watching Magee.
Kazami's later Gunpla being an Aegis Gundam-base model might be an odd choice, considering how he initially used a Gunpla that's supposedly from a sequel season. However, it also makes him in lieu with his teammates, whose Mobile Suits are known to have hidden gimmicks such as armored forms that change battle specifications (Hiroto), a surprisingly agile Mobile Doll disguised as a Mobile Pod (May) and a cartoonish dragon Gunpla that turned out to be an SD Gundam (Parviz).
Also, the name could be a reference to his changing perspective and ideology. Rather than the Justice Knight (reflecting his desire to be a "hero of justice"), his new unit is the Aegis Knight (Aegis being the name of a legendary shield, reflecting his new goal of protecting others)
Why does Kazami hate underwater missions when he has a fishing background in real life? Any boat fisherman knows the horrors and dangers of going overboard and drowning at sea.
Also, as a fisherman, he knows how dangerous the things that lurk below the water are, and understands that
Potentially another reason why Hiroto was able to defeat a Perfect Grade Strike with a Speed Grade, 1/200 scale RX-78-2 was due to GPD considering the RX-78-2 to be customized. Speed Grade kits are pre-painted on the runners for full color accuracy, not well mind you, but possibly enough for GPD's systems to recognize it as customized, as opposed the the PG Strike which was obviously snap built, boosting the RX-78-2's performance.
Another possibility is that GPD takes weapon scale into account as a metric for damage (EG, using an HG unit that carries an MG or PG weapon would equate to said weapons being more powerful, since they're much bigger than the suit). So using a 1/144 or 1/100 scale weapon on a 1/200 scale kit might mean those weapons were being boosted slightly
While the Windam and Daughtress may seem like completely random additions to Alus' army but because Alus had already been observing Hiroto, he would have seen both of them shortly before the moment he had previously pointed out to Hiroto in episode 18 happened.
The use of Death Army Mooks is a little less random - our first look at the Break Decals' effect on GBN involved a G Gundam-themed campaign involving plenty of Death Army and ultimately a Devil Gundam. It's a clear indication of what really drew Alus' attention in the first place, and how long he's been watching.
Alert viewers won't be that surprised by the ending of episode 25, when Alus decides to invade GBN to try and put a stop to the 'invaders' preventing him from protecting the planet for his Creators. Magee seems to be a Satellite Character for the team this season, but it's clear that May has been telling him everything, neatly averting Locked Out of the Loop. On top of that, Magee is one of the most well connected and respected players in GBN, and is being updated regularly by May offscreen so they can coordinate their plans. His Colbert Bump gave Kazami ten million views... in a game of twenty million players. This suggests up to half of the game's user base watches Magee's various social media feeds. As such, canny viewers might've seen the enormous ambush they had planned for Alus when he showed up coming.
For extra Irony, the one who should've seen the ambush coming long before it was even conceived was Alus himself, given that he should've been aware of the thousands of divers in GBN, and that some of them were stronger
It also subtly but cleverly displays the limits of Alus' Creative Sterility. He mustered more or less the same units as he had previously, supplementing them with high-value space battleships—unwittingly playing right into the hands of skilled mobile suit pilots, who can single-handedly sink warships as has been demonstrated countless times before in the Gundam franchise. While such warships exist for missions in GBN, they've never been depicted as especially effective, for the above reasons. If he was able to understand the context of GBN, he would've known better than to deploy and lose warships against mobile suits.
The two women of Hiroto's life, Eve and Hinata, each have a Meaningful Name pertaining to space.
Given her association with the planets that Hiroto named his Gunpla after, and her implied extraterrestrial origin, Eve's name could be short for "evening", the beginning of night, when the stars and planets are visible.
Hinata's name is written in katakana, but in most ways it's written in kanji, it usually has meanings related to the sun, our local and more personal star.
Applied to Hiroto's character arc, Hinata is the sun, but after the loss of Eve, he begins chasing the stars in the night sky while ignoring the warmth of the daytime sun that Hinata represents. After he makes peace with his past, he begins to let Hinata back into his life again. This culminates in episode 24. Hiroto has used Nepeight, the last of the armors to be used, but has to let go of it now that it has gotten them into space, and it's treated like he's finally letting go of Eve so he can move on. And given that the the Re:Rising Gundam and its Grand Cross Cannon is clearly sun-themed, it's probably not an accident that it's juxtaposed with Hinata, in full miko regalia, performing her archery ritual. And in the final episode, Hinata finally accompanies the team to Eldora, her avatar sporting somewhat longer hair in frontal ponytails and a flowing, miko inspired robe - she's taken the same place in Hiroto's heart that Eve held, but in her own way.
Alus's copycat Core Gundam (known in the gunpla line as the Alus Core Gundam) has parts kits that transform it into the Nu Gundam copy he used against the BUILD DiVERS (Known in supplementary media as the Fake Nu Gundam). He fails to use it as effectively as a human GBN player or a Newtype pilot would because he has limited spatial awareness, and is unable to coordinate the fin funnels in unconventional ways to catch enemies off-guard. This is reflected in the Fake Nu weapons kit, where only one of the funnels is actually usable as a weapon - Unlike Amuro's Nu Gundam, Alus's Fake Nu Gundam is only for show.
Episode 26 reveals that May was partially created from Eve's data after her sacrifice, and that May in turn can be seen as the embodiment of Eve and Hiroto's feelings, and thus their daughter. This could've been foreshadowed as early as the first episode - May resembles Hiroto in looks and personality enough to pass as a relative, not to mention May's hair naturally splits into ponytails similar to Eve's ponytails. Of course, this also could have been foreshadowed in episode 20, where May talks about her "Mama." While it's obviously what she calls Magee, potentially, if she has a mother, then she would have a father too.
Knowing that Sarah and Eve are reincarnations of the Alus's two Ancient friends might explain the powers they had in GBN. To be so close to Alus would imply that they had considerable technical skill in their past lives.
Riku and the rest of the original Build Divers didn't mind with Hiroto's team using their name, since May is also an affiliate of their team through Magee, which makes the BUILD DiVERS being an extension of sorts for the original. In addition, it was Hiroto who actually saved Sarah by choosing to not fire on 00 Sky. To Riku, what Hiroto did was someone as worthy of the team's title.
A key part of Alus is that he doesn't seem to fully understand what his purpose to protect Eldora entails, and the Alus Core Gundam is a perfect demonstration of him carrying out ideas he doesn't fully get:
Hiroto created the Earthree as a support unit to let his single Core Gundam change armaments on the fly, but since Alus has mass-produced Core Gundams of his own he sics on the heroes wearing different PLANETS System units, there is no reason why he couldn't just create individual specialized units based on his own PLANETS System gunpla if he's not going to make the most mileage out of a single unit as is the whole point of Hiroto's design.
Alus recreated the Earthree's beam saber holsters flipping up when armored despite changing the beam sabers from handheld weapons to built directly into the hands, so the holsters act as pointless spikes to do nothing but bring attention to what he once tried to use as a sniper (which requires not getting noticed).
The Earthree's decorative and unintrusive v-fin blocks some of the Alus Core Gundam's monoeye, with the faceplate meant to further mimic the Earthree's face blocking some secondary cameras on the cheeks as well.
Having the High Grade kit in hand will show that even the general design of Alus' Core Gundam is questionable, with armor parts that sit flush against each other (such as the thigh and hip connection) in Hiroto's version having gaps on Alus', including the front skirts slanting outward to expose the hip joints they are designed to protect.
Season 2 episode 22 shows the Seltsam horribly mutating like it was already full of DG Cells. It's been pointed out that the Seltsam modifications probably took place within GBN, and by extension Eldora, and the presence of the original Gundam Tertium on the windowsill beside Shido's hospital bed proves it wasn't done physically. Alus figured out how to synthesize DG cells.
is a a little something she's inherited from her mother Eve