Board Thread:Naruto Discussions/@comment-25139119-20140715134049/@comment-1512913-20140715192432

He died of chakra exhaustion. Brain doesn't die in an instant, it died due to lack of oxygen. Plenty of time for a hallucination.

When Haku and Zabuza were revived, they wondered if the place they appeared in was an afterlife, so pretty much pure land isn't an actual afterlife with consciousness/awareness and all.