Besides the titles, both the Crazy Ivan scene from the episode and Barn Swallow scene from the movie feature an extremely risky flight monikered maneuver utilized to escape Reavers.
When his character is killed during his team's LARP presentation, Xander says, "Curse your sudden but inevitable betrayal!" Alan Tudyk famously says the same thing as Wash in "Serenity," the Firefly pilot episode.
On Persephone, as Inara docks her shuttle with Serenity, what appears to be an Imperial Shuttle from "Star Wars" can be seen in the background sky left of center.