I used to be a mechanic at a mazda dealership, we once had a customer come back with a brand new car that had a bulge in the rear of the back of the drivers seat.I took the back apart to find a pair of hog ring pliers that had been left in at the factory..........wish I had kept them now instead of giving them to the service manager.
Things that are done out of board-um I would expect . . .
It was in the late 1960's a car owner brought their new car back for service because of an unidentified rattle. The service tech could not find the cause and dismissed it as a picky customer. After several attempts to get the problem resolved it was just accepted as nothing. Many years later when the car was having the rear quarter window worked on, a coke bottle was found inside the rear panel of the car. A note inside the bottle read. "You finally found me."