Ron Perlman said there were times during the making of 'Pacific Rim' that he thought 'the acting police were going to pull me over and ask for my credentials.'

"I would do my version, and Guillermo would say, 'I want it bigger!' " the actor said, referring to the film's director, the outsize Guillermo del Toro. "I said, 'If I go any bigger I'm going to get a hernia.' And he'd say, 'Go for it! I want it bigger!' "

Everything is bigger in "Pacific Rim," the futuristic sci-fi thriller starring Charlie Hunnam ('Sons of Anarchy'), Idris Elba ('The Wire') and Rinko Kikuchi ('Babel'), in which the nations of the world finally find common ground: Kaigu - enormous scaly monsters that rise out of the seas - are destroying cities. So the earth responds in kind - with 40-story mechanized fighting machines, which can only be piloted by two human minds, synced up and ready for action.

The movie, which opens Friday following preview screenings today, was written by del Toro and Travis Beacham, but the script is almost superfluous. What 'Pacific Rim' is about is size, scope and an almost wry response to the Hollywood studio summer- blockbuster- tent- pole epic. The film makes almost too-obvious references to the ' Transformers' films and Japanese monster movies of the '50s and '60s ('Godzilla,' ' Mothra,' 'Rodan'). It's as if del Toro set out to show Michael Bay how it's done.

But there are other allusions as well, to ' Battlestar Galactica,' 'Mighty Morphin Power Rangers' and the work of pioneering specialeffects wizard Ray Harryhausen - plus, the kind of visual flourish that has marked most of del Toro's creature- driven work, including 'Pan's Labyrinth,' 'Mimic' and the 'Hellboy' films, in which Perlman played the red, horned escapee from perdition.

This conceptual art image released by Warner Bros. Pictures shows the Knifehead monster from the film, ‘Pacific Rim.’
This conceptual art image released by Warner Bros. Pictures shows the Knifehead monster from the film, ‘Pacific Rim.’ (Associated Press/Warner Bros. Pictures)

'This was a walk in the park for me compared to the 'Hellboy' movies,' said Perlman, 'where I was the one whose performance was going to be instrumental in the ultimate audience experience, the character who was the heart and soul of the film. Here, it's Charlie who is the heart and soul. I'm in there basically for spice, the salt, the oregano.'

Perlman said he thought his inclusion, as a war profiteer named Hannibal Chau who deals in black- market kaigu parts, was actually an afterthought. ' I think they thought it would be funny having a Caucasian guy play this guy named Chau,' he said.

Like many an outsize Hollywood adventure that juxtaposes 40- story monsters and normal humans, the actors have to respond to ... nothing. Or maybe a tennis ball on a stick, which they have to stare up at with as much awe and abject terror as they can muster.

'But actors are used to that at this point,' said Guillermo Navarro, who has been del Toro's cinematographer since the director's 'Cronos' (1993). 'Pacific Rim' marks his digital debut - his first movie not shot on film.

"The real problem remains how to make the virtual environment belong to the real world," Navarro said. "You're grounding the fantastic elements with actors and set pieces. That's the connective tissue. And of course, you have to have an understanding of scale, of space, which in this case is very big, a big structure, a very big frame. It has to accommodate a huge space, and the elements have to interact within it."

Although the rise of computer imagery would seem to make this easier, Navarro said it actually demands more cooperation between departments on a film, entities that ordinarily operate autonomously.

"It becomes a weird collaboration between the art department, cinematography, all the grips and electricians and camera and visual-effects worlds, huge departments, who have a lot to do on their own but have to interact," he said. "Sometimes, the needs of the virtual images go beyond what we anticipated, and sometimes you don't see that till six months after you're shooting. It's a very long pregnancy."

And after the labor?

"Guillermo has been making monster movies on various levels all along," said Perlman, who has now made five films for the director. 

"But this is his metier and he has a complex, well-articulated version of where the monsters fall in our story telling, historically."

The key, said the actor, is that the monsters del Toro creates are often far more human than the monstrous people who populate his movies - as in the Oscarwinning "Pan's Labyrinth," where a young girl takes refuge in the supernatural from the world of Spanish fascism.

This time, Perlman said, "it's different. The monsters are monsters. And yet, they have behavioral qualities that elicit a human response.

"Some people who've seen the film already have told me they found themselves rooting for the kaiju, because there's something sympathetic about them. You don't see that in summer tent-pole movies, which are geared to impress, not to move you."

But with del Toro, he said, it's always different.