Nash: In competitive behavior someone always loses.
Charles: Well, my niece knows that, John, and she's about this high.
Nash: See if I derive an equilibrium where prevalence is a non-singular event where nobody loses, can you imagine the effect that would have on conflict scenarios, arm negotiations...
Charles: When did you last eat?
Nash: ...currency exchange?
Charles: When did you last eat? You know, food.
Nash: You have no respect for cognitive reverie, you know that?
Charles: Yes. But pizza - now, pizza I have enormous respect for. And of course beer.
Nash: I have respect for beer. I HAVE RESPECT FOR BEER!
In a scene that takes place in 1956 or 1957, Alicia Nash places an orange Tupperware container in the refrigerator. Although Tupperware first became very popular in the mid-50s, the particular model of Tupperware used in the film was not introduced until the late 60s or early 70s.
Another indicator that the people weren't real: The little girl runs among some pigeons on the ground and none of the pigeons fly off.