Gekko?
According to Wikipedia there was a scene cut from the movie that involved Max taking Gekko to the top of a sand dune at night, facing the lights of Bartertown and as the boy lies dying, tells him that they have reached Tomorrow-morrow land and are home.
I've seen this movie 3 times and never even remember seeing a kid names Gekko. I remember one scene much later when they're on the truck/train racing out of barter town when one of the kids says "Gekko was right"
Who was Gekko and when and how did s/he get killed? The only kid I remember dying was Flinn who was dragged under the sand.