They are there whenever you run the route... The spawners do other silly things too such as abruptly changing direction of vehicles. Really sloppy and needs a rework. I still find Run 8 is the best way to enjoy Cajon Pass.
All dtg need to do is change the models to Deloreans then it would appear normal. They could add in the steam engine from part 3.
Pen corridor has school buses which cut corners on the over bridges and fly above your head. Perhaps DTG have a tie in with Harry Potter and we'll see flying cars above Glenfinnan viaduct on the next Scottish route