“Moreover, his vernacular in the play places him on a lower social scale than his speech in Casablanca does…”

Ummm… No. In the US, it’s both the upper and prole classes that swear. It’s only the middles who insist on euphemisms. This highlights Kriegl’s origins as a German, and not an American. For a better grasp of this sort of thing, read Paul Fussell’s “Class,” Lewis Lapham’s “Money and Class In America,” and Nelson Aldrich’s “Old Money.”

His citations in the .PDF appear to be accurate in that they match to the pages in the script. However in this reader’s opinion, they appear cherry-picked to prove a particular point — that the play is weak, and the movie is great. That’s the official Warner Brothers’ line, and one can hardly blame them for it, but… It seems cheap, somehow.

Kriegl makes no mention that Ilsa is “Lois Meredith” and like Rick an American in the play. Far spunkier, and a much snappier character. (Presumably this was changed when Bergman became attached.) For example, if you remember the big deal about how Rick never drinks with the customers, but he breaks this rule for Lois and Victor, Rinaldo tells her, “Madame, you have just made history.” Her reply: “It isn’t the first time. You must read my memoirs.” (pg 1-33)

This raises another point, perhaps minor — it’s Rinaldo, not Renault, in the play. It’s Luis, not Louis. There are other character name changes, as well.

But the core of the story is much the same as the screenplay. Los Bros Epstein and Koch did far more of a light adaptation than a wholesale rewrite of Burnett and Alison, at least to this reader.

Perhaps a better online essay about this topic:

http://www.encyclopedia.com/doc/1G1-59599086.html