What are examples postmodern trends in Forrest Gump?

Jenny's Abuse (Dramatic Irony)

There are moments in which Forrest's intellectual limitations cause him to have a different perception from the viewer. For instance, adult Forrest recalls that Jenny’s father was a “lovin’ man, always kissing and hugging her and her sisters," which the viewer knows to mean that he molested Jenny. There is a disturbing disconnect between what Forrest understands and what we the viewer see to be true.

Antihero

Forrest finds himself in many ironic situations, but perhaps the most ironic one is when, immediately after receiving a medal of honor from the president for his service in Vietnam, he gets pulled into a line of veterans who are on their way to a rally protesting the war. Once there, he is asked to address the crowd, but the sound goes out during his speech, so no one can hear what he has to say. In this instance, there is dramatic irony, because we the viewer know that Forrest does not have a political critique of the war like the hippies who are holding the rally, but they hold him up as their hero, because they assume he shares their beliefs. It is also, in a broader sense, highly situationally ironic that Forrest ends up as a hero on two ends of the political spectrum in one day.