In the flashback scene in the van, Hurley's friend Johnny says to him, "Stay gold, Ponyboy." This is a reference to the Outsiders and this phrase being used in the book is, in turn, a reference to the Robert Frost poem "Nothing Gold Can Stay". ("Everybody Hates Hugo")
Henry Gale is the name of Dorothy's uncle. When initially captured, Ben (then insisting his name was "Henry Gale") claimed to have come to the Island in a balloon, as did the Wizard. The real Henry Gale apparently did.
The content itself is surreal, being about a man who journeys far in a dream as though in a vivid parallel dimension, only to be abruptly awoken to the mundaneness and bitterness of reality. This is a paradox uncovering that dreams can be better at revealing the truth than reality.
Locke attempts to recreate his brief sighting of the blast door map on a page from a 1939 book of poems by Alfred de Musset, called Sur les Débuts de Melles Rachel et Pauline (On the Beginnings of Miss Rachel and Miss Pauline).