The music in the movie was performed by professional musicians and set to Russell's actions, so it looks like she is really playing the compositions.

"You're never just OK at the cello," Russell told reporters in New York recently. "You're like a child prodigy at the cello, performing at the New York Philharmonic. So, I went from 'Twinkle, Twinkle, Little Star' to Bach solos in about 12 weeks. Many, many hours a day just to be able to fake the fingering … I was doing compromised versions of the Cs and the Gs, but pretty much following along and that was an extreme part of doing this film."

So has the new mom kept up with her cello playing?

"I'd love to say that I did, but I have not," she laughed. "But, I will, some day. It takes a lot of work, but they're exquisite, even just to look at."

In the film, Russell plays a cellist trying to reunite with the son she was misled to believe died at birth.