The funniest part is that his kids never aged from the moment he left them to when he saw them again.
Pretty early into the film I thought the plot was going to be all about Cobb. I thought he was actually the target for inception. Inception to create the belief needed to let go of the wife from his dreams and finally wake up to reality. That perhaps when she killed herself she was actually waking up to reality after all, not just trying to go back to limbo.
Still... for a guy who's been away from his kids for so long, I found it funny that they didn't age a day. Their hair was the same length, etc. It's like he never left. The daughter sounded older on the phone that she looked too.