Turn back now if you don't want (very) mild The Witcher 3 spoilers or are still mentally scarred from a certain statuesque episode of Dr. Who. If you're still here, then you're ready to witness the mild-confusion-giving-way-to-sheer-terror that is The Witcher 3's Weeping Angels Easter Egg.
It's actually somewhat subtle, and if you never took the Witcher Wannabe sidequest you may have missed it entirely. To find it, you'll need to journey to the cemetery just east of Lindenvale. Once you're there, you can wander into a little chapel guarded by a pair of seemingly ordinary angel statues. You can probably guess what happens when you turn around to leave, though it doesn't seem like they'll actually try to kill you - just freak you the hell out.