Each issue cover appears to be stamped with a series number indicating there are 2,148,999 variants to the cover, one for each issue of the print run. However, collectors have found only 4 different numbers:
Inside front cover.
Among the letters is one from actor Brendan Boone, star of the television series "Garrison's Gorillas", and Mad contributor Larry Siegel, complaining that his credit was left off of the parody "Sik-Teen Magazine" in Mad #121.
Cartoons drawn into the margins of random pages.
Inside back cover.