This episode was dedicated to the memory of Jim Davis (Jock Ewing), who died on April 26, 1981 at the age of 71.
Along with Starting Over (1981), this is one of only two episodes between Seasons Four and Eleven in which Ken Kercheval (Cliff Barnes) does not appear. The next episode in which he does not appear is the series' 300th episode Three Hundred (1989). His absence from that episode ended a streak of 208 consecutive episodes which lasted from Denial (1982) to The Serpent's Tooth (1989). The only actors to appear in more consecutive episodes are Larry Hagman (J.R. Ewing) at all 357, Linda Gray (Sue Ellen Ewing) at 307 and Victoria Principal (Pamela Ewing Barnes) at 210.
Bobby does a lot of diving trying to find the wrecked airplane. Patrick Duffy is right at home in the water, excelled at swimming and was the titular Man from Atlantis (1977).