This is the last credited episode of Scott Miller as Duke Shannon.
This was the last episode broadcast in color.
This was the last episode to run 90 minutes (with commercials).
This was clearly designed to be a series finale, but did leave a door open in case of a renewal. ABC did wind up giving it one more season, albeit reverting to one hour in B&W to cut costs.
Although it's never said out loud, it's quite obvious that the Moses family is Jewish, thus they and the Jamesons have to side-step around the real reason they don't want their kids to marry.