Paris (Leonard Nimoy) and the IMF's female operative, Monique (Julie Gregg) drop various clues that Paris is really the dead Otto Silff suffering from amnesia about his former identity. One of those clues is that he plays Otto's and Alena's "theme," which Monique even refers to as "Beyond the Shadow of Today." That is the real name of a composition written by Lalo Schifrin (who also wrote "Mission: Impossible's" famous theme music) for its sister program, Mannix (1967). The music was written for the similarly-titled episode Beyond the Shadow of a Dream (1967).
Otto Sliff is only seen in a file photo. He was played by daVinci, Frank who was Nimoy, Leonard's stand in on Star Trek. Here, Paris is impersonating Sliff.
The warehouse where the trivanium is stored was located in the Paramount studio lumberyard.