The police car in the beginning of the movie is number 1127. This is known as the "angel number" in various spirituality circles.
In 2014, SyFy network launched a television series called Dominion that is set 25 years after the events in Legion. In 2015, after two seasons, SyFy cancelled the series.
The name of the diner is "Paradise Falls", a reference to the changing nature of God's attitude to man and the nature of angels from protectors to destroyers. Also a nod to John Milton's Paradise Lost, where it describes the fall of Satan to earth and the war between angels and man.
Paul Bettany portrays the archangel Michael while Dennis Quaid's character is portrayed as an atheist. In real life, it's the opposite; Bettany is an atheist while Quaid is Christian.
The last production the Orphanage worked on before it permanently closed its doors in 2009.