In the E.T. cart, I don't think so. If there is a poster of any kind, it'd be an Atari catalog that folds out into a poster. You can kinda tell if you have a poster by gently squeezing the box and seeing how much give it has. Might even have a slight bulge to it...
I thought at first E.T. might have this one: http://www.atarimani...rev-a_49_2.html
...but if there's a catalog at all, might be this? http://www.atarimani...6725_289_2.html
(don't believe I've never seen the second one)
Does anyone know how Atari determined they would put catalogs in their games? Must have been a "first, second, third pressing" kind of phenomenon one would think, so maybe they put so many catalogs into the first batch of certain titles. Have no idea... always seemed pretty darned random to me. I remember thinking that by the time of the Jr., 7800 and XE releases, they were stuffing more catalog-posters into certain batches of titles.