You would have thought that one of the characters may have commented or something (another aspect of her femininity or whatever showing through)
A woman disguised as a young man, in turn of the century Poland ? unthinkable !
So nobody thought of it and didn't see it.

Hilary Swank is also a girl, but looked and acted much more masculine than Barbra in Boys Don't Cry.

Alsoand I know this is kind of an obvious answerbut, well, she is a girl.
He said it's all in your head, and I said, so's everything
But he didnt get it.

she always runs like that, knock-kneed with limbs flailing about. i think i noticed it first in for petes sake.