In case you skip it...

This episode establishes that O’Brien has built a racquetball court on DS9. Bashir joins him for a few games and turns out to be quite good - he was captain of the team at Starfleet Medical Academy and won sector championships in his final year. He trounces O’Brien, though during a rematch it’s revealed that there is interference from probability-manipulating technology and it’s not clear how a fair match would go.

Racquetball persists as a shared interest between Bashir and O’Brien who continue playing regularly.

Also, while this doesn’t matter much for Deep Space Nine, this episode finally provides a name for Guinan’s race, the El-Aurians - though it’s technically not confirmed that she’s a member until Star Trek Generations.