4-25: Broken Link
When Odo is struck with an unknown illness, Sisko seeks help from The Founders, who enact a punishment against Odo for harming another Changeling.
4-09: Our Man Bashir
A transporter mishap converts several crewmembers into spy-themed holosuite characters, with their true memories erased and their lives linked directly to the program.
4-07: Little Green Men
Quark, Rom, and Nog accidentally transport themselves back to the Roswell Incident on Earth in 1947.
4-03: The Visitor
When a freak accident traps Sisko in a time paradox, only re-appearing every few years, Jake spends the remainder of his life trying to save him.