Noah, the sloth, seems to have just been given a random name, but in the original series. The humans left Earth in fear of the Scub. When they returned thousands of years later, they found they could live on the planet again. This is somewhat similar to the Biblical story of Noah, so the name serves as a Call-Back.
Quartz is used to make watches in real life. Quartz, in the show, enables time travel and can alter history.
If Ao does in fact have an older sister, then it means Eureka and Renton have two biological children and three adopted children (they presumably still exist). In other words, Ao and Eureka are part of a family of seven.
Commercial nuclear power was never developed because of the danger it would create were a nuclear plant to be hit by a Scub Burst. However, the Nimitz Class nuclear powered aircraft carriers were still developed. That's because the Naval Nuclear Propulsion Program predates Atoms For Peace. Admiral Rickover's team developed nuclear power for naval vessels before it was put to commercial use. Since the research was still done, and since naval vessels are mobile, nuclear power was still used for naval vessels.
Ao is unfazed by the prospect of his friends not remembering him, because he knows that Naru will still like him, even if nobody else does.
All the In Spite of a Nail can be explained by the Ripple-Effect-Proof Memory of the Quartz Gun's user. That the Quartz Gun was fired is an immutable event in space-time. Therefore, the timeline must guarantee that the Quartz Gun is fired at a certain place and time, and this means that an event had to provoke its use, no matter how improbable that event is.
Translation Convention is fine, but that doesn't explain how everyone from the multi-national Generation Bleu can understand each other. Either everyone speaking some common language (probably English), or there are Translator Microbes. Then again, they do have a working AI in this setting, so auto-translation devices wouldn't be that far-fetched.
The fact that Coralians don't age was established in the original series by the fact that Sakuya's appearance remains unchanged for 40 years. The fact that Eureka's natural appearance is unchanged over the course of 25 years confirms that this was not the result of Sakuya being stuck in that lotus all that time. Now for the horrific part: the same does not apply to half-Coralians like Ao. Eureka will watch all of her loved ones grow old and die while she remains young, including Ao.
Since Coralians don't age, odds are Eureka is still fertile. Since Human-Coralian hybrids cannot survive in their world, Eureka and Renton may be left with three choices: swear off sex forever, resign themselves to watching more of their children die, or become Star-Crossed Lovers, as Eureka would have to flee to a more hospitable world every time she gets pregnant, with no guarantee of ever seeing Renton again.
You know there is something called contraception right?
