On DVD, chapter 26 is where the slip-up is located. The chapter is titled, "Attacked all around." On video, you need to fast forward to the final chase scene at about 78 minutes into the film, with Max driving the tanker. The mohawked villain, Wez, using a grappling hook and chain, latches onto Max's driver-side door and rips it off. There is a reaction shot of Max, then a pan back to the Wez, who is hollering, "Go,go!" Immediately after this, there is another shot of Max looking back. It is during this shot that you can plainly see a man crouching down to the side of Max in the cab of the truck. Maybe he's a cameraman in there for interior shots-who knows? It's definitely not the Feral Kid, as he has not been hauled into the cab yet by Max. Look for it, it's fairly easy to see.