Story colleagues told me once: requirements for a car's rear wind shield was that is had to withstand air pressures of 120km/h. But the car could not go in reverse that fast, so the requirement did not make sense and was loosened.

On delivery of the produced cars, many rear wind shields were broken. Turns out they were transported from the factory on a train, faced backwards so they could fit more cars on the train.

(no idea if this really happened, but it's a nice little story)