Illyria mentions visiting a world with nothing but shrimp. This is a nod to Superstar (2000), in which Anya and Buffy are talking about alternate realities, specifically a world with nothing but shrimp.
It was during the filming of the basement fight scene that showrunners informed the crew that the series had been officially cancelled.
This episode is Amy Acker's final true appearance as Fred, albeit in a dream sequence. She will continue to appear as Illyria throughout the rest of the series, who will oftentimes impersonate Fred for various reasons.
After guest starring as Harmony for over eight years, Mercedes McNab joined the regular cast and was finally added to the opening credits. The credits were also edited to show Amy Acker's character as Illyria rather than as Fred.
This is the final time a new member is added to the main cast.