“Mirror Image” takes place in a bus station in upstate New York — a station that is quiet and largely empty except for Millicent (Vera Miles) and Paul (Martin Milner), two strangers on their way to Buffalo. Although Serling chose a slightly different location from his real-life doppelgänger encounter, he still kept the story in a station for public transport. Airports, train stations, bus stations: they’re all notable as places where your identity is irrelevant. It doesn’t matter who you are or what you do for a living; you and nearly everyone around you are just fellow travelers, and nobody needs to know much more about you than that.
If this episode’s any indication, these are also places where your identity is at its most vulnerable. This is a problem for Millicent, because stealing her identity seems to be what her mysterious counterpart is most interested in doing. What makes her even more vulnerable is that she’s waiting for a bus to Buffalo specifically to start a new job there. She’s in a transitional stage of life, and stuck in a transitional place. If anyone’s gonna get stalked by a doppelgänger, it’s gonna be her.
As liminal space scholars like video essayist Solar Sands have noted, places like bus stations function as channels to get you from one place to another, not really designed to be seen as a place in and of itself. When you’re forced to dwell too long in these non-places, they start to feel a little eerie, a little unreal. Considering Rod Serling was stuck in one of these places during his doppelgänger run-in, it’s no surprise he started thinking about some fifth dimension located outside of time and space. That’s what all airports feel like when they’re quiet.