Researchers have shown that fake, drone-projected street signs can spoof driverless cars. Amazingly, these fake street signs can apparently exist for only 100 milliseconds and still be read as "real" by a car's sensing package. They are like flickering ghosts only cars can perceive, navigational dazzle imperceptible to humans.
As if pitching a scene for the next Mission: Impossible film, Ars Technica explains that "a drone might acquire and shadow a target car, then wait for an optimal time to spoof a sign in a place and at an angle most likely to affect the target with minimal 'collateral damage' in the form of other nearby cars also reading the fake sign." One car out of twenty suddenly takes an unexpected turn.
Ghosts Only Cars Can Perceive