I've often heard this rumor but never a definitive answer, I'll do some research and get back to you.
There are only three brief instances in which De Niro and Pacino faces both appear in the same shot: 1) the shot where Pacino pulls over De Niro and is looking out of the car window; 2) when Pacino is watching a well-hidden De Niro on a surveillance monitor outside the metals factory. Pacino's reflection can be seen beside a reversed De Niro; 3) the last scene of the film when Pacino is holding the De Niro's hand after he dies.
"It keeps me sharp, on the edge, where I gotta' be."
"Who? Who? ...What are you a fvcking owl?"
"All I am is what I'm going after."
"I'm angry. I'm very angry, Ralph. You know, you can ball my wife if she wants you to. You can lounge around here on her sofa, in her ex-husband's dead-tech, post-modernistic bullsh*t house if you want to. But you do not get to watch my f*cking television set!"
CHRIS: Charlene's going to leave me. NEIL: (quietly) Why? CHRIS: Not enough steaks in the freezer.
