@bossmonster: Going by the image as drawn doesn't help at all, IMO. I mean, in panel 1 we already see the explosion. That means the light from the explosion has already reached the place Flash is supposedly moving all these people to at massive FTL speeds, which also means all the EM radiation released should have reached most of the populace and blinded, killed, or rendered everyone in range terminally ill. A mushroom cloud also doesn't form immediately, but within a few seconds or so, a vastly greater timeframe than the 0.00001 microseconds given.
It's pretty obvious the author just wanted to have the Flash do something totally amazing, without actually thinking of what it would entail. The actual "feat," supposedly saving the entire populace of the city after a nuclear bomb detonated, using pure speed, is pretty much contradicted by both the author's statement he was moving slower than light, and by what we are actually shown, which is survivors not showing up until well after the light of the bomb reached the same location.
Moreover, I would say it is ultimately PIS anyway. There are a number of high-profile events that involved Wally just barely surpassing the light barrier, or needing great effort to do so. In Final Crisis he and Barry really needed to push it to surpass lightspeed at the end, even though the Black Racer had been pursuing them for a while. When he was fighting Zoom, he needed Bart and Gary to accelerate to lightspeed. I'm pretty sure there have been at least a couple of other times as well. Going trillions of times lightspeed is, IMO, akin to when Quicksilver was written as outrunning radio waves (i.e. its nonsense and the author didn't quite understand what he was actually doing).
Since he's going at near-light speed, we can use E = mc^2
No, that's just his total mass-energy at rest. Relativistic kinetic energy is given by the Lorentz equation E=mc^2/[(1-v^2/c^2)^1/2]. As you can see, if v=0, then the equation reduces to E=mc^2, so that is the minimum total energy an object can have. The maximum energy goes to infinity as v goes to c, and becomes undefined at v=c due to dividing by zero (and becomes complex at v>c due to taking the square root of a negative number).