Ezra, when chasing Coulton and Natalia, tells them "You’re all going to die down here." Anyone who's seen the first Resident Evil movie would recognize this as a line from the Red Queen.
Both Tir Na Eternity and Tir Na Incorrigible are based (in shape) off of a series of servers run by roleplaying groups in Second Life.
Some of the characters are based off people and characters who once played in those servers.
The Sands (and some of the occupants) are based off of or named after characters that once played in the Sands of Persia simulation in Second Life.
Mana seems to resemble the Force an awful lot, although it has been adapted a bit for use in the main plot involving the Eternity Gems and Eternity Gauntlets.
Originally, Ezra was based off of Urza from Magic: The Gathering (and even given a brother to fight, Ratava).