Judy Winslow appears in archive footage, even though she was written out of the series. Although if the show continued for a tenth season, it would've revealed that Judy had moved with Rachel to Detroit. Willie Fuffner (Larenz state) also appeared in archive footage, although he too was written off the show.
The clips shown supporting Harriette's argument in her defense of Urkel are Requiem for an Urkel, Ice Station Winslow, Dance to the Music, Saved by the Urkel, and Miracle on Elm Street
Two clips in this episode weren't from earlier episodes, including the clip shown during Eddie's story about Urkel and the clip about the Urkel Super-Vac. They were filmed for this particular episode.