Continuity mistake: The amount of bites out of the slice of pizza Chris is eating changes between shots.
Continuity mistake: When Chris is talking to Jon Favreau in his hotel room, Chris leans across Jon and grabs a pad from the end table next to him. In the next shot the pad is on the table again, then disappears.
Answer: That's not Jimmy, just a look-a-like. Jimmy's short and stout, the guy in "Christopher" episode is tall and medium built. The hair is also different.