“The document that the background actors were given was created by an outside extras casting vendor,” HBO said this afternoon amid a controversial day on the set of Westworld, its upcoming sci-fi series that had more than 55 extras in the buff and taking part in “graphic sexual situations” before the cameras.

“It was not requested, written or approved by HBO, Warner Bros. Television, or the producers, and contains situations that we do not require of any actor,” the premium cabler said. “We are rectifying immediately the discrepancies in this vendor’s document with our actual on-set practices, which provide a professional and comfortable working environment for all performers.”

Hollywood extras agency Central Casting is handling all background actors’ requirements for HBO and Westworld. Sources say no decision has been made whether the series will continue to employ the company’s services after today’s PR debacle.

HBO’s statement comes after my colleague David Robb reported today that a rare explicit casting requirement resulted in the rare step of a SAG-AFTRA representative being on the set to monitor the situation and make sure it conformed to the union’s Television Agreement.

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“This document serves to inform you that this project will require you to be fully nude and/or witness others fully nude and participate in graphic sexual situations,” said a consent agreement distributed among extras by Central Casting. “By accepting this Project assignment, you may be required to do any of the following: appear fully nude; wear a pubic hair patch; perform genital-to-genital touching; have your genitals painted; simulate oral sex with hand-to-genital touching; contort to form a table-like shape while being fully nude; pose on all fours while others who are fully nude ride on your back; ride on someone’s back while you are both fully nude; and other assorted acts the Project may require. The Project will also include language and sexual situations that some may consider personally objectionable or uncomfortable.”

The SAG-AFTRA deal states that consent by actors to appear in scenes requiring nudity or sex acts might be ended at any time, that the production’s set has to be closed to anyone not directly involved with the filming of such scenes, and that no still photography is allowed without the authorization of the background actor.

Westworld was one of 11 projects overall to be conditionally approved by the California Film Commission in June in the first round of production tax incentives under the now-$330 million-a-year program. The first season of the HBO show received a little more than $12 million in credits on expenditures of almost $54 million.

The reboot of the 1973 theme-park-robots-gone-wrong film written and directed by Michael Crichton stars Ed Harris, Anthony Hopkins, Jeffrey Wright, Evan Rachel Wood, James Marsden and Thandie Newton. The new Westworld is produced by J.J. Abrams’ Bad Robot, Jonathan Nolan, writer and EP Lisa Joy and Warner Bros TV, with the late Jerry Weintraub also listed as producer.

Westworld is expected to debut on HBO in 2016.