I've seen a player d/c during the game & their stats show 999 armor & magic resist.
I have also had the Flash bug happen to me but most annoyingly is the ranged attack bug. Noticed most on Ashe, when I try to attack a champ she'll keep running instead of attacking. Also, the worst of them which cost me many kills, I'll be following them attacking & just as they get to their tower or 1 shot from death, my champ will stop & turn to attack minions instead. Pisses me off because I never clicked on the minions I'm trying to get the champ kill. I lose the kill & they get away either cuz of the tower or now I'm stuck in a wave on minions & can't catch up to them. Happens sooo much. Happens with a lot of champs but I've noticed it the most when using Ashe.
Also, the remade Phantom Dancer does not always work. I still get stuck on minions A LOT.
Lastly, jungle bug. I was in the jungle near the golems and the enemy champ I was fighting did an aoe which hit the golems. I never attacked or touched them, I was using single target on the champ. The golems attacked me instead of them! I died & lost the kill cuz of this when I clearly would have had the kill had it NOT been for the golems attacking the wrong person.