On page 11, in 1979, it's clear that Harper and Penny have been on the lam from a pursuing Terminator and they have been "leapfrogging" out of Seattle. By "leapfrogging", Harper is likely referring to the military strategy of "island hopping", i.e. hitting/stopping at some islands in a chain while skipping others to throw enemies off the track of where you are and where you will land next. Seattle is a U.S. Pacific Coast city with numerous small islands along the coastline.

On page 12, the Pacific Motel appears to be a fictitious motel for the Seattle area.

The car Harper and Penny use in 1979 looks as if it may be a Volkswagen Rabbit.

    On page 13, the booking confirmation for a Cessna airplane rental the Terminator finds in the motel room, shows a date of 8/21/79.

    The rental slip looks as if it signifies the plane to be a Cessna 172 model (it's partially obscured by the Terminator's thumb), but the model seen flown by Harper on the next few pages does not quite match any of 172s I've been able to find in online databases. 

As the Terminator approaches him on page 19, Harper remarks, "You bastard. I knew you'd come. Grim Reaper always over our shoulder." The Grim Reaper is a western mythological figure personifying Death, typically depicted as a skeletal figure in a black hooded cloak and holding a scythe, which gained prominence during the Black Death (bubonic plague) during the mid-14th century in Europe.

Near the end of the story, Harper's skull is crushed by the Terminator, and Penny dies of a heart attack during the stress caused by the Terminator's attack. Their last names (Duggan and Penny's maiden name of Alekseev) are only later revealed in "Systems Check".