A show within Amazon’s “The Man in the High Castle” resembles “The Twilight Zone,” a speculative tale that appears to take place in a timeline closer to the one we know. It could even be our own. In the scene shown, a contented office working merrily hums along in his duties as the Rod Serling-style narrator speaks in ominous tones about the comfortable way that the world works: If he works hard at his job, the disembodied voice says, he will be rewarded. Sure enough, he’s called into his boss’ office . . . only to be met by a black man. This sight more than shocks him – he’s horrified. But his nightmare doesn’t end there, because in walks his replacement – a younger man, also black. Cue the trumpeting thriller music. Shows within shows can be clever spoofs, or they may operate as deft winks acknowledging some broader point that can’t cannot be adequately finessed within the main narrative. This small narrative aside does a bit of both. The “Twilight Zone” doppelganger is …