If you've played the game to a certain point, Nolan's plan in the pilot to defeat the Volge using the Terrasphere will sound familiar. The Defiant Few used the same tactic to defeat Dark Matter at the battle of Defiance.
Possibly accidental Fridge Brilliance: casting several British actors as the aliens and having them use generic American Accents. Possibly offering an in-universe explanation for any occasional accent slippage or pronunciation oddities? After all, these are aliens and English isn't their first language by a long shot.
Datak compares the affairs of Defiance to threads in a rug, stating that knowing how they all come together is the key to getting information. In the encounter between Nolan and Stahma after she convinces the Mayor to appoint Datak to the town council, she is seen weaving threads together during the town council's meeting. This is also much like a "spider spinning her web." Stahma has proven to be the more calculating of the two, with her threads going everywhere.
The story of Hunter Bell and Tommy is intended to be a foil to Datak and Alak. In the former, Tommy is compelled to investigate Bell's murder out of obligation to the elder for his moment of benefaction. In the latter, Alak does the opposite - defying his elder because he feels no obligation.
The reveal of Nolan's war record explains his present Chronic Hero Syndrome. He's trying to atone for the things he's done.
The foreshadowing statement Stahma makes to Kenya: "You don't know Castithans." Later, Kenya is Genre Savvy enough to bring a gun to the meeting with Stahma, but not enough to realize that Stahma is wearing gloves, and the poison is on the flask. She truly did not know what Castithans are capable of.
In the midst of his Villainous Breakdown, Datak says he misses home. Wait, back home he was a nobody, on the lowest rung on the social ladder. Why would he miss that? Well, back home, at least things made sense to him. He had a rotten place in Castithan society, but at least he had a place. Here on Earth, he has no predetermined role in society. He consequently has no idea how to act. He keeps trying to do what he believes a proper upper-class Castithan male should be doing. The things he does to get the respect and respectability he so desperately craves probably would have worked back on Daribo, and he just can't get his mind around the fact that they're not working on Earth.
Votan is a figure from Mayan legend. He was either a founder of a dynasty or a completely mythical culture hero; no one's really sure anymore, but he was an important figure in Pre-Columbian myth and legend. The Votan ship carrying the kaziri crash-landed (or did it?) in what is now Missouri somewhere around 3000 BC. Plenty of time to pass into myth and legend by the time the Mayan civilization arose. And when you consider Aztec legend that Quetzalcoatl was pale-skinned...hmm, were there any Castithans onboard that ship?
Earth is incompletely and badly terraformed because the Kaziri, which was sent ahead to begin terraforming Earth, held about 9:30 of the terraforming equipment.
The main Votan immigration fleet only had enough terraforming equipment to correct any smaller problems with terraforming, and had planned for Earth to already be terraformed by the time they got there.
That means that the Votan fleet arrived with very different expectations that what they actually found. No wonder they were shocked and surprised by so much of Earth and humanity.
While Treasure Doll's murder is being investigated, Amanda has flashbacks of relevant conversations she's had with her. However, in these flashbacks, Treasure Doll is painted in a very positive light, as a lost girl in love. Since we know that she seduced Alak, tried to poison a pregnant Christe so that she'd have a miscarriage, repeatedly asserted that she just wants a rich and high-class husband, etc. that seems dissonant - until you realize that the flashbacks are Amanda's memories, and thus we're seeing Treasure Doll through Amanda's eyes.
Castithans have pure white skin and heightened senses, especially smell. This means that it is very easy for them to tell when they are dirty, which in turn explains why bathing is such a central part of their culture.
Irathients have a reputation as smelly savages, and in fact often shun high technology in favor of a nomadic lifestyle. One of the primary benefits of civilization is medicine—and due to the fact that Irathients are immune to most diseases, that's not a problem they have to worry about, leading to them being more likely to return to nature.
It's explained that the Irathient population of Defiance fought against vaccinations for their children and were incredibly hostile for what the mayor assumed were religious reasons. Those crazy aliens, eh? In the game it's shown how the EMC were experimenting with viruses that explicitly targeted alien biology and tested it under the guise of...vaccinations for the Votan populace.
The "Strongest and Bravest" of the ark hunters have retired in Antarctica. In a business where people hold each other at gunpoint and steal each other's stuff maybe she meant the most ruthless and violent. That would make Antarctica one hell of a place. Comments in-game and out imply that Antarctica is just another desolate wasteland, with any Ark Hunters making the trip getting killed by an unknown party so word can't get back to inhabited areas. After all, it would require much more than terraforming for Antarctica to be anything other than a cold-blighted nightmare.
Assuming the organ-harvesting doctor is telling the truth, we've just learned another reason why the post-terraforming Earth is a major Crapsack World: polio, a horribly debilitating illness almost completely eradicated from the industrialized world, has returned, mostly likely due to the absence of reliable vaccinations. So not only have we lost air travel and long-distance telecommunications, we've lost modern medicine too. Lovely.
The Irathients mentioning the use of chlorine gas mass executions.
Nolan also mentions oxygen bombs that were used on Liberata (who breath nitrogen), thus likely both suffocating them and/or burning them.
Black Jonah carries what is unquestionably a ~100 year old Luger pistol. Given who he is and what he does, both the choice to carry a century-old museum piece, and exactly choosing that specific museum piece, is definitely no coincidence. Pottinger also uses one, and Berlin even lampshades her similarity to Leni Riefenstahl. (It's even more obvious when noting that Riefenstahl was young, attractive, and met frequently with top officials in the German Reich)
The Earth Republic soldiers (especially Berlin) wear uniforms that have distinct callbacks to the Hugo Boss uniform styles of the SS.
The "refueling" ship is actually a Gulanee ship. The Earth Republic was clearly intending to use these energy beings as a power source. The question is, did the Votans do the same thing?
In the 1960s and 1970s the Viet Cong were called "VC". It's probably coincidental, but the series has taken to referring to the Votanis Collective as "VC" and showing humans relating stories of casual Votan racism as well as wartime atrocities against civilians. And the E-Rep and VC are both angling for a way to restart the Pale Wars, which means showing Votans as the enemy may well prove a crisis point for Defiance.