In the last episode, why did Sara never consider using the transportation machine to bring the children to the USA to put them in a foster home or something? Abelia is shown in the first episode transporting multiple giant snake-like mechs using the machine, surely a dozen or so children wouldn't be so much of a problem. Abelia is seen at the very least cooperating with the group at the end, so she would likely be willing to use the machine for this purpose, having just done so for Shu. The USA is definitely in better shape than the desolate, broken-down Hellywood at the end of the series. Sara could have ensured that the kids survive in a home, (rather than having them continue living in a Crapsack World and potentially die of natural causes given the lack of resources) and also got to return to her parents and discuss the pregnancy. Sis definitely would have preferred the kids surviving over Sara trying to be a mother figure while only a few years older than the kids themselves.
If the world Hellywood is set in is so far in the future that the sun is beginning to go nova... how can they even communicate with people from our time, and vice versa? For that matter, why do humans in the distant future still look like humans today? Logically, even if the species stayed genetically similar, language would have evolved so far by that point that they might as well be speaking two entirely different languages.