1) The cold-hearted lack of expression by Michael, while seemingly comforting Fredo, silently communicating to Neri that the time had come for Fredo to die.

2) It's in a deleted scene, but I love the look Vito gives by rolling his eyes on the way to visit Genco in the hospital. Vito asks Michael "Did your American girlfriend get back to the city alright?" Michael answers "Tom took care of it." Vito smiles sardonically and rolls his eyes as he turns from Michael.

3) The shrugging smirk Sonny gives Connie when she is begging him not to kill Carlo. Sonny's expression says "Hey, even I'm not that cold hearted to kill your husband - the man I was responsible for introducing you to."