September 30, 2015 8:20 AM EDT

A contract requiring extras in the HBO show “Westworld” to consent to performing a variety of sexual acts on camera has union officials worried that performers won’t know they can back out.

The contract lists a number of acts that performers must consent to joining, including “genital-to-genital touching” and contorting “to form a table-like shape while being fully nude.”

In response, SAG-AFTRA, a union representing actors, posted a notice on its website telling performers that some parts of the contract may be unenforceable. Performers have the right to revoke consent to nudity at any time based on SAG-AFTRA guidelines, the union said.

Stars like Ed Harris, Anthony Hopkins and James Marsden headline “Westworld,” which will air on HBO in 2016.

Write to Justin Worland at

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