To provide evidence of the possible difficulties the narrator and his father encounter in Dragonwings, the film would need to include images of

A more diverse population, including Chinese immigrants.

Explanation:

Dragonwings is basically a work of historical fiction which combined Chinese folklore that deals with dragons, real historical events such as the immigration of the Chinese to California, the great earthquake that occurred in 1906, and also the story of a father and son that wanted to fly a plane.

In summary, the answer to the question will be that: the film would need to include images of a more diverse population which includes Chinese immigrants.