Garak's role and actions in this episode are similar to the character Danny in The Great Escape (1963). Both men were forced to work in a confined area and both suffered from claustrophobia. It is also worth noting that Andrew Robinson himself suffers from mild claustrophobia, and on the day the crawl space scenes were shot, he was suffering from the flu.
This marks the last time any of the Deep Space Nine cast is seen wearing the original DS9 style uniform that debuted in the pilot, "Emissary." The cast switched over to the "First Contact" style of uniform in "Rapture," 5 episodes earlier. The lone holdout was the real Bashir, who'd been replaced by a changeling before the change in uniforms occurred and is still seen wearing the older style of uniform at the Jem'Hadar prison camp in the Gamma Quadrant.
The Bashir-changeling's bomb was said to include Trillithium. That substance was used in the rocket Dr. Soran shot at the Veridian sun in Star Trek Generations, in which the goal was also to cause a star to go nova.
Dax is hesitant about jumping to warp inside the Bajoran star system. In Star Trek: The Motion Picture (1979), Captain Kirk had to risk jumping to warp inside Earth's solar system to intercept V'ger as soon as possible. Also, in order to achieve time-warp velocity by slingshotting around the Sun, Kirk and crew traveled at warp inside the solar system again in Star Trek IV: The Voyage Home (1986) (they even initiated warp speed while still in Earth's atmosphere for the return trip). And don't forget The Picard Maneuver.
Footage of "Bashir's" runabout departing the station is reused from the pilot, "Emissary."