Kosinski talks about the 3D in the film:
Our approach is not like "Avatar," which I think is 3-D from the first shot to the last. Ours is sort of a "Wizard of Oz" approach. Ninety-eight percent of the 3-D is in the world of "Tron." The 3-D really starts once we get into the Tron world.
About Jeff Bridges' two characters:
Jeff is playing two characters. He's playing Kevin Flynn, the character from the original film, and he's playing Clu, the avatar that Kevin Flynn created in the 1980s. I'd say he's Clu 2. There was a Clu in the first film who looked like Jeff but was very simple in terms of his abilities. He's very stiff. Clu 2 is a second incarnation of Kevin's avatar. He doesn't only look like Jeff, but he can think like him too. So it's a whole new level of artificial intelligence.
What they felt they needed to retain from the original:
The focus was always to serve the story we are telling. To include Bruce Boxleitner is not at all a cameo or stunt casting. He is integral to the story we're trying to tell, which is why he's in it. We've taken the events of the first movie as historical facts. In our story, Kevin Flynn emerged from his first experience as CEO of ENCOM and actually released the Tron video game based on his experiences in the first movie. ENCOM has become the most innovative, most successful, most forward-thinking digital company in the world as of 1989. There are fun references to parts of the first film. Sam Flynn [Garrett Hedlund], in searching for his father, has to retrace his steps and comes upon clues and places that we visited in the first film, like Flynn's Arcade. Even in the world of Tron itself, a lot of vehicles and sequences have evolved. We'll get to see how the disc game has changed, how the light cycle battle has changed. We get to see the new version of these iconic sequences. Things have gotten bigger and a bit out of control.