I came across two bugs, one being the invulnerability at the end of the game, the other being tower aggression.
For invulnerability, I was Nasus,all ulted uphammering against the enemy nexus, an enemy fizz tries to kill me and a yasuo, and he e's (invulnerable then), but then i killed nexus (+50g) and the victory screen plays. He came out of his e, than started taking damage from my ultimate, and ended up dying. I got +300 gold (does not really matter about the gold) but it is just a bug in the game. Since he came out of his e invulnerability, he lost the endgame invulnerability.
For the tower aggresion i was Kennen under tower range, and I q'd (shuriken) a severely low kha-zix mid leap, and killed him while still being under tower. Tower was only focused on minions, and then remained focused on minions.