After "Flipper" ended, Halpin appeared in feature films, including as Stu MacRae (teen son of Richard Greene's starring character) in Ivan Tors' "Island of the Lost" (1967), as Bo (student radical who befriends a teenage girl travelling on a European bus tour) in "If It's Tuesday, This Must Be Belgium" (1969), as Keith (First Mate on a shabby vessel chartered for a tour that stumbles on 'living dead' Nazis) in iconic niche horror movie "Shock Waves" (1977) and as Ken Wilson in "Flipper" co-creator Ricou Browning's "Mr. No Legs" (1979). Halpin's guest appearances on television in the years shortly after "Flipper" were; as Kenny Carter, Jr., in the Carl Betz series "Judd, for the Defense" (1968), as a celebrity contestant on "The Dating Game" (1968), as Ben Cabot, Jr., in "Bracken's World" (1969), as Greg in Ivan Tors' "Primus" (1972), and as Eric Bates in "Caribe" (1975).