The proximity of the Atlas-class booster to the ranch house.
In the movie the launch of the Atlas-class booster takes place
about 100-200 yards from the ranch house without settling it ablaze
or leveling it. Farfetched indeed.
But...There is an anecdotal story from the late aviation expert,
Martin Caidin [JimO may have known him], who as a younger
man in the early 1960's claimed to have sneaked upto within
400 yards of a Titan missile launchpad at Cape Kennedy
and witnessed the launch of such a missile.
He claimed he only suffered temporary deafness and
second-degree burns to his face from such a foolhardy
stunt.
Jacob