Crisis and doom
There are elements of horror, especially around the issue of apocalypse. The novel explores several different kinds of minor apocalypses, from the criminal feudalism of rural Mexico, to the fictional (one would hope) organ harvesting—where humans are "harvested" and their organs are sold on the black market. The most interesting apocalypse from a literary perspective is the minor apocalypse of traffic on the Harbor Freeway. The scene obviously plays on the feelings on experiences in severe traffic jams, but the plot is not so unthinkable.
Literary mastery and influence
In the opening to the novel, the novelist does something interesting behind the plot—she potentially admits her influence. There is a man named "Murakami" who directs traffic in the post-apocalyptic car city of homeless people. He is described as a "sensai" which implies mastery and it implies apprenticeship. There is famous Japanese author by that name who was well known in 1997 when this novel was published, especially in California. Also, there is another clue to consider this—"Buzzworm" is the character who ensures Emi and Gabriel's success in reporting, by giving them vital information from his real life. This is yet another portrait of accepting the influence of other people.
Surrealism and borders
The idea of surrealism is plainly evident in the plot, because there is all that mysticism associated with the sacred orange and the Tropic of Cancer. Then, there is another minor mythology presented that has the same surrealistic effect—Bobby's desperate quest to save Rafaela, a woman in serious danger whose son is literally named 'sun,' but in Spanish, Sol. These are obviously playing on mythological interpretation, but within the plot itself. The "borders" of reality are being erased, just as they are in other aspects of the plot. Consider how little the arbitrary borders of government matter in this plot, when compared to the higher order of nature.