Well, we'll have to disagree on Casablanca - I think it's a beautiful version, especially with the black & white atmosphere. Could be more serious, I guess, but it's still Topolino material, several years before PKNA (which made it easier to go into that whole "grey area" thing and to break some taboos)...
Btw, I wonder if Casablanca is the only Disney comic that was designed to be printed in black and white and isn't a newspaper strip.