His q sometimes disappears at its end, which sometimes leads you to question where it might be or if you are lagging.
After you die, his return q does no damage. I know this isn't intentional, it was doing damage a few patches ago.
His homeguard animation doesn't stop after he the effect wears off, he keeps walking in slo-mo. He has to stop walking and then start again.
When the W is land and ekko ults, the W doesn't proc based on the actual trail, rather the circle of aoe damage that his ult has. So, you can w, use ult, and proc a stun and shield without ever going through the area once. Not sure if intentional, but looks a bit too strong.