With the films budget they could have sourced a small nuclear bomb the size of the original Trinity test and detonated it just for the movie. Just make sure the camera is rolling as it's a one take shot.
I’m in Australia, so it’s only a (relatively) short drive to Woomera.
We should make sure our (the West’s) nuclear deterrent still actually works, and put the fear of God back in to everyone.
And also demonstrate how relatively benign the fallout from a thermonuclear weapon is, ie. relatively little radioactive material is generated from modern nuke.