One of the lines most closely associated with the film—"Play it again, Sam"—is a misquotation. When Ilsa first enters the Café Americain, she spots Sam and asks him to "Play it once, Sam, for old times' sake." After he feigns ignorance, she responds, "Play it, Sam. Play 'As Time Goes By'." Later that night, alone with Sam, Rick says, "You played it for her, you can play it for me," and "If she can stand it, I can! Play it!"
Rick's toast to Ilsa, "Here's looking at you, kid", used four times, is not in the draft screenplays, but has been attributed to something Bogart said to Bergman as he taught her poker between takes. It was voted the fifth most memorable line in cinema in AFI's 100 Years...100 Movie Quotes by the American Film Institute.
Six lines from Casablanca appeared in the AFI list, the most of any film (Gone with the Wind and The Wizard of Oz tied for second with three apiece). The other five are:
- "Louis, I think this is the beginning of a beautiful friendship."—20th
- "Play it, Sam. Play 'As Time Goes By'."—28th
- "Round up the usual suspects."—32nd
- "We'll always have Paris."—43rd
- "Of all the gin joints in all the towns in all the world, she walks into mine."—67th