Before we give any props to the screenwriters, we have to give a prop or two to Murray Burnett and Joan Allison, who wrote the play the movie was based on (entitled Everybody Comes to Rick's). However, be sure not to give them excessive proppage, as the play was never produced, and it was a minor miracle that it ever caught anyone's eye to be turned into a movie in the first place.
However, once it ended up on producer Hal Wallis' desk and he decided it belonged on the big screen, the rights were purchased for a then unheard of amount for an unproduced play—$20,000. Today, most writers dream of making that much in their entire lifetime. Well, the writers who spend most of their time shining shoes, anyway.
Assigned to the film were screenwriters (and identical twins) Julius and Philip Epstein Philip was still building his résumé, but Julius already had an Oscar nomination under his belt, for Four Daughters, and would go on to get several more. Despite having a contentious relationship with Jack Warner (you can probably figure out how big a deal he was based on the last name), their talent was impossible to deny, and Warner was forced to put up with the notorious pranksters' various shenanigans. Moral of the story: if you're going to put a bucket of water over someone's door, make sure you've the talent to back it up.
A couple other writers helped out on the original draft (Howard Koch, who took the Epsteins' early efforts and did a ton of fleshing out) and with subsequent revisions (Casey Robinson and others), but the bulk of what ended up in the movie was, conceptually, the brainchild of the Epsteins. They (along with Koch) would go on to win the Oscar for Best Writing, Screenplay, taking home one of the film's three Academy Awards that year. Of course, the real prize was getting to hear their words quoted more often than those from any other film in Hollywood history.
"Hasta la vista" is fun and all, but "Play it, Sam" is classic.