Axis Mundi (the axis of the world) is the connection between heaven and earth in many religions. This is presumably how many people in the show's world view Jarden.
Another shift in season 2 was the decision, influenced by the positive reception of the Matt and Nora POV episodes in season 1, to limit the number of POV characters in any given episode, providing greater focus in the storytelling.
The new main titles are reminiscent of the G.R.'s Christmas Day PowerPoint presentation in the book, in which Departed individuals have been "clumsily deleted" from photos, leaving a "pale gray blob."
Mark Linn-Baker appears as himself, a once-popular actor who - on this show - faked his own disappearance.
In the opening credits, a football picture appears over producer Peter Berg's name. This is a tacit acknowledgment to Berg's highly lauded TV series Friday Night Lights (2006) which this show's creator, Damon Lindelof, has cited as a major influence.