Two added scenes overseen by Brad Bird were animated for the theatrical release of The Iron Giant: Signature Edition.
The Signature Edition adds two new scenes that were storyboarded for the original film, but were never fully animated. In the first, Dean and Annie have a conversation at the diner right before the farmer sells dean the tractor with the bite taken out of it. In the second, the Iron Giant has a dream in which armies of Giants take over and destroy a world.
In the original, Hogarth finds the Giant's hand watching the TV, showing an advertisement for Maypo Cereal. Director Brad Bird initially wanted an ad for the Disneyland attraction Tomorrowland. Disney would not not grant clearance to use Tomorrowland footage back 1999, when the film was originally shown. Years later for the Signature Edition, Disney allowed the Tomorrowland footage to be used. So in the Signature Edition, the TV shows an ad for Tomorrowland. Oddly enough Brad Bird directed the film version of Tomorrowland (2015) for Disney, which was released the same year as the Signature Edition.