don't need to worry; if it pops it won't hurt you--probably won't even reach you. The danger is if a metal fitting breaks and a piece of the fitting is flung back at you or the tube. Plain rope is so seldom a danger it's not a worry.
Even at speed...if the rope breaks, it will just fall into the water. I have seen ski ropes break and they might recoil a couple of feet, but nothing to be concerned about.
