How is “a needle in a haystack” used?

In Room (2015), one line is: “Yeah, it's a needle in a haystack.”

Which movie is “a needle in a haystack” from?

The clip at the top of this page is from Room (2015).

a thing that is almost impossible to find

Heard in 4 moviesPlay Idioms

Oxford100% of films
a thing that is almost impossible to find
Like a needle in a haystack.

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

Yeah, it's a needle in a haystack.

Said in 6 films · #1