When asked about performing with the markers, Jim Carrey, who plays Scrooge and the three Christmas ghosts, said, "There are certain aspects of the technology that are so exciting and amazing creatively that you can't wait to see what it turns into. Certain aspects of the technology make things easier, to get a lot of scenes done, to do a lot of material at once. There are a lot of aspects that allow [Bob] to create the world that he wants."

"For an actor, there are extra challenges. You have to create the ambiance and the belief in your surroundings in your head," Carrey added. "You can use everything you got. The fingers turn into these long spindly looking things. It's like puppeteering in a way."

Colin Firth, who plays Scrooge's nephew Fred, was only on-set for two days. For his experience, he said when your performing the challenge is that it's "a whole run, a whole scene with no reason to stop. You're never off camera. If you stumble it's in the movie. In some ways you had to rise to the occasion of having all that freedom. There is no proscenium. There's no camera to play to. But having said all that, it's fantastic. It's even more authentic than doing theater because there is no imaginary fourth wall. Or even if you're doing theater in the round, you have to worry about the people in the gallery. Or you have to worry about the marking or blocking. You can do exactly what you want at any time."

Robin Wright Penn, who plays two roles in the film, is a vet of performance capture, having worked on Beowulf. As for the advancement of the technology, she marked, "Even more so with this one, our eyes, every movement and the minutia of the acting that we all did, you see on the screen. And yet, we could change the size of the eyes with the animation. I said at one point, what if I could look like one of those Whoville girls with those big ole blue eyes. And [Robert] said, 'We can do that.' Your every movement is captured and it's fascinating to watch. It really comes through. It's so moving."

As for the stereoscopic 3-D elements, she commented, "It's like watching a 2D performance, but you feel like you can reach out and grab Jim's hand and feel the snow falling at the same time. You're actually in the environment. That's what's so incredible about it."

Having worked on Who Framed Roger Rabbit?, Bob Hoskins is not new to working on technically challenging films with Zemeckis.

Bob Hoskins, who plays Scrooge's former employer Fezziwig, worked with Zemeckis on the revolutionary Who Framed Roger Rabbit? Commenting on the difference between that film and this one, he said, "Before everything had to be dressed and we shot the film and then they blew up the frames and painted on the characters. With this they shot all the performances and then they paint the background, put on the costumes, and do everything. So it was the complete reverse. And what was extraordinary was the fact that once you're covered in all this stuff you got nothing else to do but to concentrate on your performance. They've taken all responsibility from you. It's extraordinary."

Carrey added, "There were times when as film actors, you're use to having the proscenium in your head somewhere and there are boundaries, but in this there are no boundaries anymore. It's odd not to have any boundaries. Once in awhile, I'd say to Bob, 'Can you just stick a camera there? Just so I can feel someone, because I'm use to having someone.'"

On that Zemeckis said, "I learned this early on. I put a marker on the camera and then it becomes a character, and immediately I'm creating shots in the virtual world, but what it also does for the performances [is that] the camera [becomes] a dance partner. The camera is another performer, so the camera creates rhythm, so the actor feels the camera moving from here to here so he knows when to deliver the line. So that is a very helpful tool because we've all been trained in having that camera as a partner."