Rachel Nichols portrays the same character, Nicole Noone, originally portrayed by Sonya Walger in the 2004 film The Librarian: Quest for the Spear (2004). A throwback scene from the end of Quest for the Spear is used to replace Walgers with Nichols.
The aria sung during the chase scene in the Paris Opera House is "Queen of the Night" from Mozart's "The Magic Flute".
The Arlene Schnitzer Concert Hall, a historic theater in Portland, Oregon, stood in for the Paris Opera House. The episode's scenes there were filmed on the afternoon and evening of Wednesday, Nov. 26, 2014. This coincided with a protest march through the streets of Portland (including outside the theater) decrying the shooting of Michael Brown by police in Ferguson, Missouri. The chanting of the crowd, which could be heard inside the theater, delayed the shoot as the theater went into lockdown until the streets had been cleared by police. It was after midnight before the shoot wrapped.
Features guest appearances by stars from two long-running science fiction series of recent years: Rachel Nichols of Continuum (2012), and John Noble of Fringe (2008).