 The "original" Buck Rogers of the 1930s (from  _Buck Rogers (1939)_ (qv)), Buster Crabbe (qv), made a guest  appearance as Brigadier Gordon in episode #1.3 "Planet of the Slave  Girls" (he was most famous, of course, for playing the title role in  _Flash Gordon (1936/I)_ (qv) and its sequels).