ANAHEIM, CALIF. - "I didn't believe in the supernatural before this movie," Olivia Munn said of her latest "Deliver Us From Evil." The actual footage from the New York Police Department of real-life exorcisms changed the actress' mind. "I'm a full believer [now]."

Speaking to HitFix from WonderCon last weekend, Munn said that her co-star Eric Bana warned her about these tapes, that he couldn't sleep for three weeks after watching them all. "I watched only half of one tape and I had to stop," she said.

Some tape. Director Scott Derrickson actually re-enacted footage of that one scene she saw for the film, which -- for at least one of Munn's friends -- was effectively scary enough that he'd happily never have to see the film again.

Watch the rest of the interview with Munn above, on what she wanted her audience to get about the "home base," on the real-life police officer Ralph Sarchie and more.

"Deliver Us From Evil" will be out in theaters on July 2, 2014.