I wonder..

It's difficult to determine what's past and what's happening in the present. How old is everyone now? I wonder what Linda really thinks of her husband. Is she aware of his affair?

Denial

In the later scenes, the audience might get the idea that Willy cared too much of his pride, popularity, and being well-respected. That goes for his children too. Willy stressed being "well-liked" rather than accepting the possibility of failure to Biff. This being in the past could be a foreshadowing of their current unhappiness. Also, the audience sees Willy's manipulation of reality. He attempts to deny it and exaggerates the truth. He is simply unable to accept the truth about himself and the reality of the world he lives in. He denies his own failure because it is easier to invent a reality in which he is successful which explains his current disorder.