Continuity mistake: When Adriadne and Cobb sit down, a newspaper stand explodes, but in the next shot it's still standing.
Continuity mistake: As they are sitting around, planning the next job, Cobb is wearing a blue shirt, of which he rolls up the right sleeve repeatedly.
Continuity mistake: When Arthur is shot in the head, at first there's no bullet hole in his head, but in the next shot there is.
Answer: The answer above is solid and I agree, but there's another plausible way of looking at it. It is implied at the end that Cobb could still be dreaming (we never see if the top stops spinning). If that's the case, then he would likely dream his children to be exactly how he remembers them.
jshy7979