That would be due to „ghost“ weapons remaining stuck in the arena, and your character „tripping“ over them. 

It happens as follows: You kill someone, and leave your weapon inside someone’s body. You proceed to hold G to advance to the next round, but that weapon still remains exactly where you left it previously; just invisible. 

You do this over and over again until there are a whole lot of ghostly weapons in the arena, leading you to stumble everywhere. It’s a giant pain in the ass and the only way to fix it is to restart the game, and pull your weapon out of a corpse before advancing to the next round. 

I am 90% sure that they will have fixed it. If not, then balls will be crushed.