Also, remember when he breaks the sad news after Vito says, "My wife is crying upstairs." Tom replies with, "I didn't tell Mama anything."

Oh but HERE'S a "did anyone notice" that I just picked up on.

During the Five Families meeting, keep your eyes on Tom. It's interesting his reactions, esp. as he's coldly staring down that pimp Tattaglia. At this point, he's under the impression that he's looking a the man behind the murder of his brother Sonny. Also, when Barzini sez "Then we're agreed..." He seems a little taken aback by it, while some have said this, for Vito, was the tipoff that Barzini was the culprit. The acting by everyone in that scene was golden.