What are some of the postmodern themes that are evident in Death of A Salesman? Give specific evidence.

Two aspects of Miller's Death of a Salesman seem to signal its postmodern elements.
First, the fragmentation of time is common in postmodern literature. Willy repeatedly loses himself in memory, but Miller's detailed staging directions suggests he wanted the audience to find themselves somewhat lost as well in this fragmentation. When feeling especially helpless, Willy falls back into scenes of the past when Biff still embodies hope and when Ben offers a sense of approval for which Willy is so desperate. The expressionist staging suggests that these scenes are not merely back filling a story line but are meant to be seen as central to the fragmentation that the modern man experiences in a dehumanizing world.

A second post-modern element concerns the general bleakness in Willy's story as well as those of his family. The Loman men lack heroic qualities, admirable dreams, or strength of character yet in "Tragedy and the Common Man," Miller argues that these common or even lowly figures attain to a certain heroism in their ability to continue striving for a better life. Both Willy, and to a lesser extent his sons, represent the "indestructible will of man to achieve his humanity" despite the impossibly degraded possibilities a mechanistic life offers.
http://movies2.nytimes.com/books/00/11/12/specials/miller-common.html