A friend of mine back in the late 70s was driving his brand new Lada home from the garage when as he signalled to turn right a car exiting that road pulled out in front of him.A 'discussion' ensued during which the driver asserted my friend had signalled left. It turned out he had indeed signalled left, as the indicators were wired back to front so moving the switch to the right indicated left and vice versa!
He returned to the garage using hand signals (Remember them?) for them to correct it. It turned out about half of the cars on the showroom floor were wrongly wired.