Dramatic irony and race
To the extent that this novel comments upon dramatic irony and race, it is primarily negative. The criticism against Bob's character is clear: Bob is unqualified to work constructively toward racial harmony because he is absolutely naive about race relations and his inherent privilege. While some people are desperate to make ends meet, he is presented multiple, often lucrative opportunities, and he acts as if that is automatic and normal. This is a subtle use of dramatic irony; the reader knows that Bob is unaware of what privilege means in the deep South.
The ironic guilt
It is too moralistic to determine whether Bob is guilty in any way for his decision to kill an armed invader when Eddie's liquor store is being robbed. Bob does well by his obligation to the liquor store, but taking a human life is never easily reckoned. There is a dramatic irony about his guilt because the reader has to use their own opinion about race relationship and death to judge him. This is additionally layered because it makes the novel's plot into a kind of thought experiment for the reader.
Vanise's ironic innocence
Another commentary on character must be derived for the novel's secondary protagonist. As a prostitute, Vanise's life is shaped by moral compromise, but without knowledge about her life, the reader's judgment is also a commentary on their own opinion, because technically, dramatic irony forbids the reader from knowing enough about Vanise to judge her by her profession alone. As far as the novel is concerned, Vanise's use of compromise seems ethically oriented around obtaining a healthy life.
Globalization and change
The novel comments in an ironic way on globalization and the way that has changed human life and will continue changing it. The irony starts with the title of course, whose namesake is the symbolic opposite of globalization. As the continents spread further and further apart, the theory is that they will end up converging again the reverse side of their motion, but as for now, the continental drift is away from itself. This is an ironic way of suggesting that globalization will lead to a second Pangaea.
The drama of crime
Bob has a tendency to mischief that is exacerbated when he trips over a criminal enterprise. The way that Bob falls into a criminal smuggling operation is littered with irony. It is ironic because it is accidental, and because the dramatic tension of the novel is brought to its peak by the dramatic irony of suddenly seeing a basically normal guy turning into a career criminal. The "Breaking Bad" slide shows that Bob's character leaves a lot to be desired, but the novel offers him a chance at redemption when he accepts death and does the right thing.
