"A fleshy metonym for the various 'holes' in Inland Empire, Niko's 'hole' is the Heim-like womb that is a standard trope for the uncanny; it is the rabbit hole of time through which Dern slips; and it is the very real hole wreaked upon the female body by a sadistic sexual violence."
Jennifer Pranolo, "Laura Dern's eternal return" (Screen 52:4 Winter 2011, pp. 477-492: 492)
Lynch described the film as about a "woman in trouble"; such a woman could be said to be "in a hole". Inland Empire seems to be full of holes which the viewer must speculatively fill; the slippages between narrative levels are wormholes, linking space and time without passing through the interim zones. But either the presence or absence of holes can be catastrophic: without certain holes in the body we would die (see Jill Masterson's death in Goldfinger), while other zones must be kept separate – Niko is dying because sex & shit have been joined in the most literal way.