Possibly the longest acting relationship on American television, and certainly in this series: The scenes with David McCallum and Robert Wagner mark a 47-year span the two have acted together, starting with numerous episodes of Colditz in 1972; McCallum was also a guest star on Wagner's hit series Hart to Hart in 1983.
Francois Chau and Ping Wu were both in the voice cast of the American version of "Godzilla 2000."