Juliett Higgins makes a comment to Magnum that Robin Masters is not Charles Foster Kane. In the original "Magnum P.I." (1980-88), Robin Masters is played by Orson Welles. Welles also famously created and portrayed Charles Foster Kane in the classic "Citizen Kane" (1941).
At the end of the episode, Magnum observed that Higgins is reading Robin Masters' first book, Queen's Gambit. That is also the name of the boat that sunk and left Oliver Queen stranded on an island in Arrow (2012).