This was the first movie to use go-motion, a variant of stop-motion animation, in which parts of the model (in this case, the dragon) were mechanized and the movement programmed by computer. During shooting, the computer moves the model while the camera is shooting, resulting in motion blur, which makes the animation more convincing.
George R.R. Martin, author of the "A Song Of Ice And Fire" novels, upon which Game of Thrones (2011) is based, has said that Vermithrax Pejorative is "the best dragon ever shown on film." One of the deceased dragons mentioned in the 1st season of the series, by Viserys Targaryen, was named "Vermithrax".
The story has many familiar dragon motifs found throughout Western culture, in particular, "St. George and the Dragon", in which maiden sacrifices were made to appease a harassing dragon. St. George's tale also includes a sacrificial lottery resulting in the surprise condemnation of a Princess. St. George is also frequently depicted with a magic (blessed) lance or a sword.
According to sculptor Bill Basso, who worked on the 2002 post-apocalyptic fantasy movie Reign of Fire, the dragons featured in the film were designed as updated versions of Vermithrax, being rendered more robust and dinosaur-like.
Graphic artist David Bunnet was assigned to design the look of the dragon, and was fed ideas on the mechanics on how the dragon would move, and then rendered the concepts on paper. It was decided early on in production that as the film's most important sequence would have been the final battle, it was deemed necessary to design a dragon with an emphasis on its flying abilities. According to Bunnet, "Designing a dragon isn't just a matter of sticking wings on a dinosaur... Vermithrax is 40 feet long, with a wingspan of 90 feet. But she had to look light enough to fly. So most of her weight is at the head, neck, and shoulders. The rest of her is pretty streamlined."
Although conceived as a creature of magical origin, screenwriter Hal Barwood envisioned Vermithrax with various rules of evolution kept in mind; for instance, making her a four limbed animal, in concordance with vertebrate biology. Barwood himself was inspired by the body plan of the Jurassic pterosaur Rhamphorhynchus. As well as following Barwood's directions, Bunnet also designed the dragon to have a degree of personality, deliberately trying to avoid creating something like the titular creature from Alien (1979), which he believed was "too hideous to look at". Specifically, he incorporated a bony ridge over the eyes, which swept over the temples and merged into the horns, giving the creature a notable frown. He also modeled the articulation of its jaw on that of rattlesnakes, as a single pivot jaw made it look too duck-like. In keeping with the necessity of the dragon being aerodynamic, its feet were modeled on those of birds, specifically chickens.
After Bunnet handed his storyboard panels to the film crew, it was decided that the dragon would have to be realized with a wide variety of techniques: the resulting dragon on film is a composite of several different models. Phil Tippett of Industrial Light & Magic finalized the dragon's design, making several cosmetic changes, such as making the wings more bat-like rather than pterosaur-like. He then sculpted a reference model which Danny Lee of Disney Studios closely followed in constructing the larger dragon props for closeup shots. Two months later, Lee's team finished building a sixteen-foot head and neck assembly, a twenty-foot tail, thighs and legs, claws capable of grabbing a man, and a 30 ft wing section. The parts were flown to Pinewood Studios outside London in the cargo hold of a Boeing 747. Brian Johnson was hired to supervise the special effects, and began planning both on and off-set effects with various special effects specialists.
After the completion of principal shooting, a special effects team of eighty people at ILM studios in northern California worked eight months in producing 160 composite shots of the dragon. Chris Walas sculpted and operated the dragon head used for close-up shots. The model was animated by a combination of radio controls, cable controls, air bladders, levers and by hand, thus giving the illusion of a fully coordinated face with a wide range of expression.
Phil Tippett built a model for scenes in which Vermithrax was required to walk. Tippett did not want to use standard stop-motion animation techniques, and had his team build a dragon model which would move during each exposure rather than in between as was once the standard, the process named "go motion" by Tippett recorded the creature's movements in motion as a real animal would move, and remove the jerkiness which was common in prior stop motion films.
Ken Ralston was assigned to the flying scenes. He built a model with an articulated aluminium skeleton in order to give it a wide range of motion. Ralston shot films of birds flying in order to incorporate their movements into the model. As with the walking dragon, the flying model was filmed using go-motion techniques. The camera was programmed to tilt and move at various angles in order to convey the sensation of flight.
Ken Ralston designed the dragonets with the assistance of graphic novel illustrator David Bunnett. In designing them, Bunnett attempted to find a look that did not inspire sympathy, in order for their deaths to be more acceptable to audiences. Realizing that most young animals look appealing due to their large eyes, Bunnett designed the dragonets to have relatively small eyes, with Ralston refining the design to incorporate bulldog and bat-like features to their faces, as well as hinting at their adult forms by adding a small horn on their noses and giving them long forelimbs that would grow into wings. Ken Ralston, Chris Walas and David Carson built three articulated puppets and a featureless miniature model (for the scene where Vermithrax discovers her dead progeny). The dragonets were operated as hand puppets through holes in the floor on set.