The blaster stops working if you move off your dot. A message comes over the speakers if you continue moving. Team Members can help escort you off without even stopping the ride if you don't listen. If you cause too much problems, the belt can come to a slowly progressing stop so no one gets hurt or falls. They have thought of all of this, I am sure.
The lag issue happens to me on Smugglers Run all the time. Especially in moments where a lot of sprites/particles are being rendered. With over 100 people's blasters blowing up and interacting with screen media all at once in real time on this one, it's going to take some tweaking for the machines to be able to keep track of it all.
The reality of these things are often not as interesting as we probably think in our minds when we hear they're "having issues," but it's a relatively simple problem that will require people smarter than me to work out, and time. But it's not the end of the world.
Also, this attraction is likely going to be cloned for other parks, so they must have faith in it.