25 Behind the Scenes Facts from Pacific Rim

Regarding his character's look, Charlie Day said, "He wants to look rock and roll, and occasionally he does look rock and roll, and then on other frames he does look like Rick Moranis. One of the original concepts was that my parents were these scientists who had created the Jaeger technology. I sorta made the assumption that he has a chip on his shoulder about scientists never getting any of the credit or pats on the back for saving the war. He really rebels against Burn Gorman's type of labcoat and bow tie-wearing scientist. He thinks these guys are rock stars, so he wears leather coats, bracelets, combat boots, he has tattoos, yet his intelligence betrays him left and right and he's a bit dorky."

According to the films writer Travic Beacham, an earlier version of the script would have Mako (Rinko Kikuchi) and Raleigh (Charlie Hunnam) speaking two different languages for the majority of the film. After connecting as pilots, they would slowly begin to understand each other, and before the end would hear one another speaking in their own respective languages.

The only remnant of a language barrier between the characters in the film is in the scene where Raleigh talks to Mako in Japanese, surprising her that he knows her home language.

In Hungary, the trailers for the movie could not mention the name of the main robot, Gipsy Danger. The name was seen as offensive against gypsy people, who form a large ethnic group in the country. In the dub of the movie itself, the name is spoken out freely, but it's left in English. This works out because it's a reference to a type of airplane engine, not the people in question.

Gipsy Danger is named after the "de Havilland Gipsy" aircraft engine. This was intended as a nostalgic nod to the World War II era, which was a major influence in the design of the robot.

"Robot Porn" is how del Toro describes the look of the film.

He went on to say, "It doesn't want to be a dystopian, existential summer movie that took a genre that was well-loved and showed you the dark side of mankind."

In March 2013, YouTube channel "Dumb Drum" created a sweded (low budget) version of Pacific Rim's trailer. Less than two weeks later, Guillermo del Toro commented on the video at WonderCon 2013, calling it a "masterpiece" and saying that it inspired him to create the second trailer for the film. He also invited the filmmakers to the Hollywood premiere.

When the film was released on home video, Legendary Pictures contacted "Dumb Drum" and asked for their help promoting the release. In October 2013, they released several sweded versions of scenes from the movie. These new videos were made in a 15-second length for easy sharing on social media websites.

One of the art directors said this is the first time they dressed a set using forklifts and jackhammers. Much of the set is made with real materials, unlike most sets.

Not Godzilla, not the Power Rangers, but a dense fog. Travis Beacham, the screenwriter, got the idea for the movie while walking along the California coastline on a foggy morning. The shape of the pier looked like a creature rising from the water, and he imagined a large robot waiting on the shore to battle it.

The Kaiju's voices are comprised of layer upon layer of animal roars and growls which were filtered, sped up, and slowed down to create the roar of alien behemoths. Then, to add emotion and a sense of intelligence, supervising sound editor Scott Martin Gershin and director Guillermo del Toro added samples of their own voices.

When the Gipsy Danger is fighting the second Kaiju in Hong Kong, it punches through a building and sets off a set of Newton's Balls (or Newton's Cradle). The scientist that the Kaiju was chasing is named Dr. Newton Geizler.