On page 2, Captain Carlin states he lost the damaged UFO over the Appalachian Mountains. This is a mountain chain that runs along much of the eastern United States, including along the Kentucky-Tennessee border as also mentioned on this page.

Colonel Foster is again referred to as Major Foster in this story.

A Yellow Cab takes Foster to Kennedy Airport. Yellow Cab is a name now belonging to multiple companies across the United States that operate taxi services in their local areas under the name Yellow Cab. John F. Kennedy International Airport is in the New York City borough of Queens.

A SHADAir transport takes Foster to Louisville Airfield, Kentucky. It is now known as Louisville International Airport and shares its site with Louisville Air National Guard Base.

Foster and Gillman drive a SHADO Mobile to Boonestown, on the state line of Kentucky and Tennessee. As far as I can tell, Boonestown is a fictional community, probably meant to be named after the legendary Daniel Boone, known for his exploration of the American frontier in what is now the state of Kentucky.

On page 3, panel 2, the mileage sign reads "Boonstown" instead of "Boonestown" as stated in all other references. 

UNANSWERED QUESTIONS

What was the alien's purpose in attempting to capture a SHADO agent (with the help of the hillbillies)? His UFO was non-flyable, so he couldn't take the prisoner back to his planet unless he had a means of communication with his people to pick him up very soon, which he did not seem to have. Was he hoping to use the agent as a hostage, essentially a bargaining chip when other SHADO personnel showed up?