Actually, I read that the Mother’s shocked and giggly response to the duck and said’s decapitation was real. Apparently, the actress had not been told what to expect.  One of my favorite parts of the movie and probably authentic to the times since Chinese food was not as mainstream, as yet, in the 30s and 40s. Even now, that type of presentation would get a reaction from me, since I’m not particularly sophisicated culinarily.