Set during World War II, the film focuses on an American expatriate who must choose between his love for a woman and helping her husband, a Czech Resistance leader, escape from the Vichy-controlled city of Casablanca to continue his fight against the Nazis.

Sam was played by Dooley Wilson, a professional drummer who faked playing the piano.

Bergman's official website calls Ilsa her "most famous and enduring role".

When Ilsa, Rick's former lover, spots Sam in the nightclub, she asks him to play "As Time Goes By." Rick storms over, furious that Sam disobeyed his order never to perform the song, and is stunned to see Ilsa.

RICK: How can you close me up? On what grounds?
RENAULT: I'm shocked, shocked to find that gambling is going on in here! [a croupier hands Renault a pile of money]
CROUPIER: Your winnings, sir.
RENAULT: Oh, thank you very much.

Everybody Comes to Rick's was bought unproduced by Warner Brothers for a record figure of $20,000 (equivalent to $350,000 in 2017). Although Casablanca was a huge success, the play wasn't produced until 1991 when it ran at the Whitehall Theatre in London for six weeks.

Rick slips the letters of transit into Sam's piano.

When they met and fell in love in Paris, Ilsa believed her husband had been killed attempting to escape from a concentration camp.

The last line of Casablanca is often misquoted (and the name Louis, pronounced 'Louie' (in French), is often mis-spelled as Louie). The correct line, spoken by Humphrey Bogart, is: "Louis, I think this is the beginning of a beautiful friendship."

RICK: I remember every detail. The Germans wore gray, you wore blue.
ILSA: Yes. I put that dress away. When the Germans march out, I'll wear it again.