This issue has variants.
Mislabeled #497 on cover. From Bob Rozakis, DC production manager at the time: "The price box was picked up from the ADVENTURE COMICS DIGEST. As I recall, we told the printer to strip in the price from ADVENTURE and they took the entire box." (via e-mail, January 1, 2011.)
Inside front cover. Table of contents.
from Showcase (DC, 1956 series) #37 (March-April 1962), #37 (March-April 1962), #37 (March-April 1962), #38 (May-June 1962)"The Flaming Doom" and "The Nightmare Menace" printed as one long story.
from Showcase (DC, 1956 series) #39 (July-August 1962), #40 (September-October 1962)combined with "The Day the Metal Men Melted" into one long story.
in Super Adventure Album (K. G. Murray, 1976 ? series) #4 ([Circa 1976-1977])inside back cover
Back cover. Promo for the interior stories.