When May looks into the mirror, she (and the audience) see a white, red-haired version of herself reflected back (White May).
This represents of a unique aspect of being a transracial adoptee – that our self-concept and our appearance can be drastically different.
The mirror motif also references a term in the adoptee community – “racial mirroring” which refers to the importance of transracial adoptees having people around them who look like them growing up, which can help foster a sense of belonging, community, and teach them about important racial issues (such as the many forms of racial discrimination) that their parents might not be aware of.
The final scene of the film features a surreal “fight” between Asian May and her reflection – a struggle between two worlds.