Not just cheating, intermittent power and internet connectivity issues, teams were not in a booth so they could see the big screen, had sun shining on their own screens apparently.
I have a friend who was there. He said it was absolutely horrid. They had to start over several matches because of issues and over six hours had only about 3 'completed' matches. Riot majorly dropped the ball.
Interestingly they wouldn't have had any of these issues if they weren't trying to further monetize the game by hosting the competition at an outdoor open venue.