Continuity mistake: At the end of the show, Tony is making an ice cream sundae for himself and A.J. He gets a Path-mark store brand aerosol can of whipped cream. When the camera cuts to closer look at Tony the can changes to a Redi-whip brand of whipped cream. (00:49:00 - 00:50:00)
Revealing mistake: Closing scene. Tony and his son are in the kitchen making ice cream sundaes. The second time Tony holds the can of whipping cream over the boy's mouth, the kid actor looks off camera for direction.
Visible crew/equipment: When Tony goes to Christopher at the construction site, the crew and a boom operator holding a boom mic are reflected in his car's door when he opens it. (00:03:34)
Continuity mistake: While Tony is talking to Melfi about A.J, Melfi's lipstick color darkens halfway during the conversation. (00:12:37)
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.