Jenilee Harrison has the distinction of playing the only character to be killed off twice. Jamie Ewing Barnes was killed off the first time in the last show of the "Dream Season" when she was blown up in her brother's car. The second time came midway through the next season, when she was killed while rock climbing in Mexico. Though the second death didn't occur on camera.
Following the conclusion of the season, the characters of Angelica Nero and Matt Cantrell were never referred to again as if they never existed. Mark Graison is never seen again in subsequent seasons which presumes that he remained deceased.
By appearing for eight seconds and uttering the words "Good Morning," Patrick Duffy became the only performer, besides Larry Hagman and Ken Kercheval, to appear in all fourteen seasons of Dallas.
JR's plan to blackmail Mark Graison for his role in a college fraternity hazing death never materialized due to the dream season.