The reappearance of Jubal Early's spaceship, which made an appearance in "Trash", which was seen near a floating island.
Joss Whedon named the bounty hunter "Jubal Early" after hearing that Nathan Fillion is related to the general, who died in 1894. Jubal Early is also the name of a ferry between the Maryland and Virginia sides of the Potomac River.
When the Firefly series was released on DVD, this episode was placed as the series finale. However, according to the official companion, this episode was originally filmed between "War Stories" and "Trash", but Joss Whedon and Tim Minear felt that this episode best summed up the series. If you watch some of the other episodes, you will notice that they let slip some of the things that should've been discovered in this episode: for example, in "The Message", Jayne mentions that River is a psychic, which Jayne doesn't learn until Objects in Space (although the audience and Simon Tam learn of her psychic ability in the much earlier episode "Safe"). Similarly, in the episode "Trash", River says that she can kill Jayne with her brain, which is supposed to be based on River having psychic abilities.
This episode takes place a few months before Serenity (2005), which is based on the television series.
The final episode of the series. The series was canceled in December 2002.