Where they really dropped the ball:

From the point they stepped outside the house was one long drawn out ball-drop. But specifically:

relatively minor nitpick:
--"It feels petrified." It looks more like scorched. What does "petrified" feel like, except... stony? And what does that mean for the boundary to be 'petrified?' Would grass 'petrify?' Not simply from passage of time, it would disintegrate. The grass outside the boundary isn't "petrified," despite the fact that it has ostensibly experienced as much time as the boundary itself. Dirt and stone doesn't 'petrify,' it is already... 'petr.' If the notion was that the electromagnetic field or whatever caused the grass to petrify instead of disintegrating then there should have been grass that looked petrified instead of what looked like charcoal or glass or whatever those chunks were supposed to be. What we saw didn't look such that "It feels petrified" really made much sense IMO. But that's small potatoes:

--The ground on both sides of the mark looks identical! Perhaps it would appear that way from within the circle, (and they should have made that clear) but from outside it should have looked different. The camera angle is from outside when it pans out, heck, even when he is touching the ground the camera seems outside the circle, but the immediate ground looks identical when it absolutely should have looked different. The neighborhood is bombed, but it is not at all apparent that it is any different than they thought it would be, because there is no clear difference. The house they are in is intact, but so seems the house next to it which appears to be outside the boundary. There is a bunch of trees that, when the camera pans out, should have been made to appear completely different on both sides of the boundary but seem identical. Maybe this was all deemed beyond their budgetary ability to do, but then they shouldn't have done the scene at all!
That shot, where the camera pans out from the circle should have shown a stark contrast between within and without if, in fact, his hypothesis was correct. It seems meant to have much greater impact than it does. It should have had. That would have given more of a "twilight zoney" feeling than it did. (as per the comment this was originally going to be a reply to.) It seems meant to suggest that the outside is far more war-ravaged than within, but that isn't as clear as it should have been--as far as we know, the world is already war-ravaged, isn't it? How are we meant to distinguish degrees without a more solid reference?
There's a van parked just outside the boundary, ostensibly the one the intruders arrived in. Perhaps they should have shown it from within the boundary, dingy and beat up but intact and only minor or no rust, and then from without as a rusted out or bombed wreck.
There is a whatchamacallit, little fortification just outside the circle but nothing to say that is any different than it "should have been." They might have shown clearly that it wasn't there looking from within, or shown it in completely different condition.
It could either have panned from within the circle to outside showing a stark contrast in one (apparent) shot, or alternated within and without with a couple or several shots with clear examples of differences.
As it stands that shot really does nothing to confirm the notion of time outside the boundary being any different from within.

--The above discovery should have impacted what followed! They go outside for what is meant to be a startling revelation, only to proceed with no apparent actual impact. There should have been some kind of discussion of how the discovery affected the importance of the machine in the war. For all they knew, the war was over! For all they knew they were all that remained of humanity!

"There's a safe house two blocks north, it's marked as contaminated, it isn't..."How could he possibly know that, when at _least_ three years has (hypothetically) passed outside?

I had more, but I took a break and lost my train of thought. Maybe later.
But I will leave you with this:
"The ARQ is off! if you die, you die forever!"
Oh, and If the ARQ is off... Why does restarting it loop back to the beginning instead of starting a new loop? Or why does it loop at all without a short? Wait, does Sonny's face short it? Why is there no evidence of electrical anything when his face is being smashed against it? Why doesn't it electrocute Ren?