"play it again sam" is the biggest misquote of lines ever. Neither Ilsa or Rick ever say that in the film.

Ilsa says "Play it Sam, play "As Time Goes By"
Rick says "If she can stand it, I can. Play it!"

However, Capt Louis Renault has the best lines:

How extravagant you are, throwing away women like that. Some day they may be scarce.

We musn't underestimate American blundering. I was with them when they blundered into Berlin in 1918.

Rick Blaine: And remember, this gun is pointed right at your heart.
Captain Renault: That is my least vulnerable spot.

I'm afraid Major Strasser would insist.

Just one from Grouch in "Horsefeathers"


Wagstaff: Tomorrow we start tearing down the college.
Professor: But Professor. Where will the students sleep? Wagstaff: Where they always sleep. In the classroom.