"Terminator Salvation" won't hit theaters until next summer, but thousands of fans got an early look at a portion of the film Saturday.

Director McG presented never-before-seen footage during a Comic-Con panel and offered a few hints about what to expect from the highly anticipated fourth installment in the "Terminator" franchise.

For example, Arnold Schwarzenegger could be back.

"The T-800 model indeed is part of the mythology of Terminator," McG said coyly, referring to the machine model California's governor played in the first three films.

James Cameron, who directed the first two "Terminator" films, and special-effects master Stan Winston, who died in June, also each had a hand in the film, McG said, adding that Winston made a cameo appearance.

"He wrestles one of the hydrobots," the director said.

The movie, currently shooting in New Mexico, could end up with an R rating rather than the rumored PG-13, McG revealed.

"We put the picture first at all times," he said. "If it's an R-rated picture, it's an R-rated picture and that's that."

He acknowledged that the studio is responsible for some of the online rumors.

"We release, like everyone else does, misinformation campaigns," McG said. "One of the joys of going to the movies is not knowing what's going to happen."

The brief clip shown Saturday was filled with explosions, tanks, gas masks, guns and crushed skulls.

Set in 2018, the film is dark and apocalyptic, "exploring what the world is like after a nuclear holocaust," the director said. "We wanted everything to feel like giant Soviet tanks crushing all comers."

"Terminator Salvation," a Warner Bros. release, is set to hit theaters in May.