Ghost Rider director Mark Steven Johnson explained how star Nicolas Cage transforms into the spectral biker.
"We film Nic or his double, dressed as the Ghost Rider, with the spikes, chains, leather and everything on him. But he wears an interactive light collar around his neck, sometimes a whole green helmet, and that's what we're going to be removing," Johnson told Comics Continuum. "So it is the person, it is the actor, but the head itself is CG. And that was our biggest challenge, making sure it looks absolutely fantastic.
"And being able to use fire as a way to give expression, which you can't with a skull. You take the shadows of the fire and the way the fire moves to give expressions and moods, which is really great because you can't get that in the comic. You can see it change before your eyes.
"When Ghost Rider's angry, he'll go white-hot with flame. When he gets sad, it will literally go blue. There's a way you can use the fire as an extension of his personality," Johnson said.