In that episode, Jadzia and Worf are on a mission to track down a defecting Cardassian officer. Jadzia is badly injured, and ...

Turns out, that in cold blood, O’Brien took a phaser and shot one Cardassian through the head. In the present, O’Brien tells Bashir that this moment haunts him, saying, “He wouldn’t have ...

A running joke of Deep Space Nine was Odo's aptitude for the 'Cardassian Neck Trick.' What this is, exactly, remains unknown. However, there were clues throughout as to what it actually looked like.

Those two alien races were prime actors in Deep Space Nine. There’s also a Cardassian officer at Vance’s big Starfleet meeting. The episode has some Mirror Universe references as well.