When they were in the Nightclub watching the exotic show, Geary asks Fredo how he knows about the place, and Fredo replies that " Johnny Ola knows these places like the back of his hand!"
At that moment watch Mike's reaction, the sickening look that he gets on his face realizing that his own brother set him up for the hit at the Nevada compound. (Earlier Mike had introduced Ola to Fredo and Ola says " We never met!") Then Mike turns and looks at his bodyguard and the bodyguard then leaves the club to go and kill Ola and Roth. Another great piece of acting by Pacino, not saying one word, but just by his facial expressions you know exactly how he is feeling inside.

Don Cardi