If that's the case, then we'll figure out hax
My personal fanfic.
Thinking for a moment, Tim picked up a ball.
"Diane," Tim began,"If the computer can simulate the universe, can it tell what I'm doing ten seconds from now?"
"Why yes, I implimented that feature last monday." Diane replied.
"Can you have it show what I'm doing one minute from now?"
"Yes, I think so." Diane set the simulation to one minute from now.
"What does it show me doing?"
"By the looks of it, you're holding a ball?"
Tim threw the ball he was holding out a window. Promptly, the simulation in the computer ended.
"And that solves that."
Was thinking about this... I don't think this would break the simulation. All Tim did was observe a lower level iteration and then make a choice that broke consistency with it. That lower level simulation would continue to run, even if on a deviated continuum from higher level iterations. Since every iteration above them also just performed the same experiment and simply chose to do something different from the one directly beneath them, the whole thing would be inconsistent all the way to the top.
Or it might just be every other iteration that is inconsistent with the one above and below it, since I think it's safe to assume that Tim was going to take a binary approach. If he witnesses himself holding the ball, he'll throw it. The iteration above him would observe him throwing it, and choose to hold onto it. The iteration above that would observe himself holding it, and choose to throw it. And so on.
So there would be an odd sort of scattering. I'm also getting the vague notion that there would be a really bizarre cascading effect on the time synchronization through the spectrum of simulations, but I'm having a hard time wrapping my head around it. Every iteration would initiate the experiment at exactly the same time, but afterwards, each iteration would be operating a minute ahead of the one before it. But I guess it's not like they're actually nullifying that minute. It's still simulated. They're just fast forwarding through it. Still, at the very top of the simulation ladder, there is a "real time". If the people at the top looked ten iterations beneath them, would they still be seeing one minute into the future, or would it be ten?