Pathing through minions when clicked on an enemy champion.
Pathing loses its mind if you right click on an enemy champion and your champion has to go through minions.
I've had pathing move my champ left and right, left and right around a single minion, multiple times.
I mean, obviously, just don't click on enemy champions to move in the best path. Even in the open it often won't chose the most optimal route.
This in combination with minon block in general is insane. How many of us were in a completely safe position, only to discover our champion pinballing through our own minions, taking 5 times longer than normal to cover the distance, and ded.