Being able to transport modular cars to the Junkyard via train can create another job to keep players engaged.  The problem arises when the train begins to move and the cars flip/bounce out.
It would be nice to have something that would keep those cars in place inside the walls of, for instance, the Trainwagona prefab once lowered/dropped in via the Magnet Crane so they can be transported to another area of the map to be shredded or otherwise done with what they please.
If it's any consulation, the shreddable trucks that are scattered around the Junkyard also flip/bounce out of the trainwagon.