According to Robert Hewitt Wolfe, Seyetik's terraforming technology is based upon the Genesis Device as seen in Star Trek III: The Search for Spock.
Mark Gehred-O'Connell's original pitch for this episode involved Bashir meeting a mysterious woman who keeps disappearing. He goes to his colleagues for aid in tracking her down but he discovers that no one aboard the station has ever seen her except himself, and as such, he has to unravel the mystery alone, as his crewmates begin to think he's imagining the whole thing. Bashir ultimately discovers that the woman is in fact a projection by a woman who is abused by her husband. This original version of the story was more of an adventure/mystery than a romance.
This episode marks the first appearance of the USS Prometheus in Star Trek. Although the exterior of the ship clearly shows it incorporates components from the Galaxy-class, not a single piece of any standing set from The Next Generation appeared. The wall outside Seyetik's quarters is a single length of stock Starfleet wall built specifically for DS9 scenes, Seyetik's quarters are a brand new set built from the remains of the runabout aft section seen in TNG: "Timescape", and the bridge is a re-dress of the USS Excelsior bridge set from Star Trek VI: The Undiscovered Country, combining its forward and aft walls. This smaller starship bridge would continue to be seen throughout the series as the bridge of various ships, both Federation and not; it would later appear in DS9: "The Jem'Hadar" as the bridge of the USS Odyssey.
The scientist's mission in this episode is to reignite a star. The starship he's assigned to is the USS Prometheus, named for the Titan God who stole fire and gave it to humanity in Greek mythology.