>I thought that the show got cancelled mid-season with episodes
>still in the can that eventually ran on syndication, including
>the episode where Tupac shows up as Jada's ex-boyfriend from
>Baltimore. I think the last actual episode was the one where
>Billy Dee was playing an old negro league baseball player.

The episode list has the one with Lena Horne as the last aired episode, and Dwayne and Whitley were both in those "new class" episodes, so I think NBC just aired the series finale to coincide with the de facto end of the season. I believe that the "new class" ones aired after the series finale, similar to what "Saved by the Bell" did that same season (episodes with Tori after the graduation ep, I believe), both of which makes their runs in syndication seem out of sequence.