Why do Shannon and (once he knows what's going on) Mario keep calling Harry "Harry"? He's not Harry - he's John Holland. Holland is mentioned at the beginning but after that the fact he's the guy in charge is totally ignored.
Host: (opening narration) Magic is an art based on deceit, on illusion disguised as reality. Tonight Mario Devlin will question what he's always taken for granted, the difference between artifice and reality. Because tonight Mario will get his first real magic lesson in The Twilight Zone.
Host: (closing narration) There's a place where blind ambition is forced to see. A place where if you're not careful, that climb to the top will age you beyond your years. But it's also a place where those who believe in real magic can stay forever young. A trick whose secret lies hidden deep within The Twilight Zone.
"Harry Kellogg" is an in-joke reference to Harry Keller, a famous magician who performed the Spirit Cabinets routine.