The mold Hal ate as a child was the same mold DMZ is synthesized from
The mold Hal ate was described as sickly green speckled with points of yellow, orange, and red. Now, DMZ is synthesized from a rare mold that is said to only grow on other molds...
The Incandenza Brothers were modeled after the Brothers Karamazov.
Hal, the tormented, witty rationalist, reminds me a lot of Ivan; the sweet-tempered, forgiving Mario, whose actions are occasionally Messianic, call Alyosha to mind; and Orin, who fucks pretty much everything that can be fucked, is sort of a modern-day Dmitri. On top of that, Hal and Mario's conversations about cynicism and idealism are, in a way, reminiscent of Ivan and Alyosha's debates about religion. Given that Foster Wallace was a huge Dostoevsky fan and explicitly mentions Karamazov towards the end, I'm pretty sure this was intentional.