This is one of the few episodes (if not the only one) with an indisputable error in its storytelling. While handling the Ralphie situation Christopher states that he has heard about Pie-O-My's death in the fire accident. This is an important detail because in this context it is quite obvious that Christopher knows from the beginning that Tony is the one who must have killed Ralphie. There is however no way Chris could have heard about the accident. Who should have told him and when? By the time he is torn out of his delirium by Tony's call nobody else was informed. Tony knows that - which makes it even worse! Hearing Christopher talk about Pie- O-My's death could therefore only lead Tony to the conclusion that Chris himself has set the fire. Given the impressively elaborate writing process as told by the writers themselves on the DVD I really wonder none of them realized the problem there. The story just doesn't work that way. Unnecessary to add that I'm a huge fan of the Sopranos. Otherwise, I certainly wouldn't care.