Jadzia Dax was not a part of the mission, despite her intimate knowledge of Klingon culture, because Terry Farrell was allergic to the Klingon make-up.
Kira tells Bashir, regarding her pregnancy: "This is still your fault." This is an in-joke about the fact that Alexander Siddig (Bashir) was the father of Nana Visitor's (Kira) baby in real life.
This isn't the first time Rene Auberjonois has donned Klingon ridges. The first time was as the traitorous Colonel West, in Star Trek VI: The Undiscovered Country (1991).
It is in this episode where it is explained in Sisko's absence Kira is in command of the station, while Worf commands the USS Defiant.
Although they are never seen very clearly on screen, the various statues in the Klingon Hall of Warriors were designed to give an overview of Klingon history, with the statues representing the heroes of different eras; for example, both Kahless and Chang are included.