This episode introduces Jessica Bowman as Colleen Cooper, replacing Erika Flores. With the exception of the episode "Bone of Contention", Jessica Bowman plays Colleen for the rest of the series run (and movies).
Beginning in 1680 comets were discovered by telescopes leading to world's end proclamations and hysteria just like what is shown in the show.
The Comet shelter that Jake builds is a nod to the fallout shelters than many Americans built during the Cold War. They prepared to survive underground for months after an attack with an atomic bomb.
Cloud Dancing is wearing a shirt that looks like a sunrise or sunset. It is a status symbol.
The opening montage has changed. This is due to an actress change.