This episode is dedicated to Derek Garth (22 July 1946 - 16 December 1996). Prior to working as a grip (lighting and rigging technician) on DS9, he was also a grip on other Universal productions. He died in a car accident.
This is Melanie Smith's first appearance as Ziyal, after the character had been portrayed by two different actresses in previous installments.
Sisko says that "professor Kahn of the Trill Science Ministry" has found a way to seal the wormhole without harming the aliens within it. This is no doubt Lenara Kahn, Dax's former spouse, who appeared in Rejoined (1995), and was established as a wormhole expert.
Garak makes disparaging remarks about Earl Grey, the favorite beverage of Jean-Luc Picard in Star Trek: The Next Generation (1987).
While trapped in the Jem'Hadar camp, Dr. Bashir proves he's human by passing a blood test. Worf questions whether the blood screenings can be trusted. He's right to be suspicious, as one of his fellow inmates is General Martok. A changeling disguised as Martok passed multiple blood screenings while infiltrating the Klingon Empire and influencing it towards war with the Federation.