Continuity mistake: When the Iron Giant follows Hogarth home they cross a railwayline and the Giant starts to eat the steel rail. During this scene you can see the distance of the railway sleepers changing from a fair distance apart to close together over the course of the shots. In the same scene you can also see that, although there is a crossing with lights, no vehicle could possibly pass as the rail has no crossover facility at that level. (00:24:30)
Continuity mistake: When the Iron Giant first learns to talk, he picks up a huge boulder that wasn't there earlier. The boulder was in a pretty big hole, but when Hogarth walks away the hole has disappeared.
Kent Mansley: Two nights ago, at approximateley 1900 hours, S.A.T com radar detected an unidentified flying object entering Earth's atmosphere, losing contact with it two-and-a-half miles off the coast of Rockwell. Some assumed it was a large meteor, or a downed satelite, but my office in Washington received a call from someone reporting an actual encounter with the object. This is no meteor, gentlemen. This is something much more serious.