Four Is Death: You can make a fun drinking game out of the number of times four is mentioned.
Gainax Ending: "Had the Ghost Dance worked, you'd be dust." And of course the novel itself has one. To understand, John dies, but the killer, who until now has been implied to be John, is still on the loose. The easiest solution is that Reggie was the actual killer.
Good People Have Good Sex: After he finds out that his girlfriend hates Indians, Reggie has angry sex with her for a week, for the sole purpose of the cosmic irony of her bearing an Indian child.
Conversely John, upon finding a white man watching Asian porn, is disgusted by it.
He Who Fights Monsters: Where to begin? Marie assumes David is hitting on her out of some ethnic fetishism and is therefore a racist... because he's white. John wants to kill a white man as revenge for all the Indians who were killed. Mather thinks he's fighting racism, while being racist in his own way. Reggie wants revenge on his abusive father by killing white men. Aaron wants to avenge his brother by killing Indians.
Karmic Death: The people who killed David did it over casino money, and then are killed over an illegal poker game.
Leitmotif: An odd example of a literary one. John's leitmotif is the sound of sandals walking on sand.
Man in White: One took John away from his family in his fantasies.
Mood Whiplash: Alexie calls the book "a feel-good novel about interracial murder".
A Nazi by Any Other Name: Truck starts talking about eugenics near the end of the book. He goes farther than Jensen's recommendation to pay people $100 for every IQ point below 100 in exchange for voluntary sterilization toward forced sterilization.
Occidental Otaku: Done American-style. (Called "Twinkie" or "wannabe" colloquially.) Many, many well-intentioned white characters have a fascination with Indians.
Proud Warrior Race: When it's discussed as to what tribes drink which sodas, a Coeur d'Alene corrects the lecturer and says they just drink blood.
Psycho Rangers: Though neither Reggie's gang nor Aaron's is really "good", they both commit hate crimes against the other ethnic group, they're both in groups of three, and they both ultimately have one guy say What Have I Become? and tell the police.
Take That: Much of the book is such, but especially the Native American literature class. Truck Schultz is also a Take That to conservative talk show hosts, especially since Truck only says such things for ratings.