Continuity mistake: Tony, Carmela and AJ are meeting with AJ's college tutor. Partway through the meeting AJ is asked to leave. When AJ stands up he is wearing beige coloured trousers, but as the shot changes to show him walking out the door, he is now wearing black trousers. (00:15:30)
Continuity mistake: When Tony sits by the pool, the position of the towel on the chair changes through shots.
Continuity mistake: The table with the beer bottle by the pool gets closer to the chair after Tony sits down.
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.