They were “additional photography”, according to Joseph Kosinski
“All in all, it just amounts to a couple of minutes over a two-hour film, but it’s those little details… That’s one of the benefits of having 18 months of post on this movie. We got to sit down and actually watch it and still have nine months left to say, ‘All right, let’s go tweak this, this and this, and remove this,’ and it helped.”
He also insists that amongst all the eye-popping action, the film is actually a drama about a father-son relationship. Which does set the alarm bells ringing slightly, because that’s exactly how director Stephen Hopkins and star William Hurt tried to sell Lost In Space way back in an interview in SFX 40, and look how that turned out… Still, at least with Tron Legacy we can go into the cinema safe in the knowledge it's free of comedy-CG-space-monkeys.