The hatch Rom is waiting to open to sabotage the Dominion's plan has the label A51/This is a restricted area on it. This is a reference to the famed Area 51 military base in southern Nevada. Area 51 was seen in the fourth season episode "Little Green Men".
Casey Biggs (Damar) is a member of the Enterprise Blues Band, which writes and performs songs about Star Trek. The other members are Vaughn Armstrong, Richard Herd, Steve Rankin, William Jones, and Ronald B. Moore. Biggs plays the rhythm guitar, and sings some of the back-up vocals.
Jeffery Combs has the distinction of portraying eight different characters on Star Trek series. He has played the roles of Brunt, Weyoun, Shran, Tiron, Kevin Mulkahey, Penk, Krem, and a holosuite guest. He is one of only five actors to play seven or more different characters in the Star Trek franchise, the others being Randy Oglesby, J.G. Hertzler, Vaughn Armstrong and Thomas Kopache. Coincidentally, Combs has appeared on Star Trek with all four of those actors.
The trivia items below may give away important plot points.
Salome Jens makes her first appearance as the Female Changeling since the Season Four finale "Broken Link". In that episode, Odo presumably infected the Great Link with the morphogenic virus he was infected with by Section 31 in "Homefront". If the virus was 'de-activated' when Odo became a solid in "Broken Link", then it seems likely that the Female Changeling reinfects him when they link. This would explain why she begins to exhibit symptoms earlier than he.