Thanks to the online sleuthing of That Mall's Sick And That Store's Dead! (aka Sickmalls) one could check the Virginia Film Office location site & find interior & exterior shots of the vanished mall.
Unfortunately, though the location page still exists for Walnut Mall, the pictures are gone. Perhaps deleted--I can't say for sure.
UPDATE 29 Sept 2008--Forget what I wrote above and try this link for the VA Film Office pics of Walnut Mall:
(Thinking out loud: If these images
Thankfully, an informative Labelscar post about Walnut Mall still has two cool pics from 1991. While some things had likely changed, I know these pictures revive my own faded memories of the mall (of Thalheimer's and Peoples Drug, in particular) as it was in the early 1970s.
Also the Labelscar post links to aerial images of the area that still (so far) show the old Walnut Mall.
Sometimes it's good when things lag a bit and information is not so up to date.