It is not too clear in that photo, but perhaps someone incorporated the rear doors into the body to make it seamless in the quarter panels? I don't see any rear door hinges or defining lines/shadowing marking the front and rear edges of the rear door. That would make the section behind the front door seem excessively long, as "ronn" suggests. But if the rear doors were "glassed" in or welded in, how would passengers get in and out of the backseat area? Lord knows, the front door openings in a '28-29 Phaeton are barely wide enough for the driver and front seat passenger. The rear seat passengers would have to climb over the front seat! Now, THAT'S real convenient for all concerned! And then, too, one wonders: Why go through all that effort to seal up the rear doors? To what end? It will NEVER be confused with a true two-door (1930-31 Deluxe) Phaeton, for Pete's sake! A closer view of this car would be helpful. Was it only shown in the film from a distance?
Marshall