Continuity mistake: During the scene when Sam and Dean enter the abandoned shipping warehouse to save Charlie, you can see Charlie's legs crossed while sitting in one shot, but in the next shot they are uncrossed. (00:27:10)
Revealing mistake: Dean borrows Charlie's phone to call Sam. On the phone, the lock screen can be seen, showing that he never entered in any number.
Answer: Over the next few episodes, it is revealed that something is not quite right with Sam - that his soul is missing since he returned from Hell, and he does not feel any emotion or attachment to his brother.
Sierra1 ★