What is the most commonly used phrase in English that came from a movie?

I see what you did there.

IIRC no cop ever cried out to a perp “FREEZE” before “The French Connection” came out.

The use of “X is toast” apparently originated in the original Ghostbusters.

I am more likely to use “KLAATU. BARADA. N**cough**. There, I said it.”

ETA:

Dammit, should have read to the end…

While I agree that “that’s what she said” is now inextricably linked to The Office, it also was at least semi-regularly used by the SNL-skit-and-movie
Wayne’s World.

Garth: “Hey, are you through yet, 'cause I’m getting tired of holding this”
Wayne: “Shyeah, that’s what she said”

The intonation is definitely distinct from Michael Scott, however.

That goes back to at least World War I: