Sure--bird eggs have to be turned so that the membranes do not attach to the inside of the shell, which can prevent the embryo from developing properly--but reptile eggs are actually 'designed' to do exactly that in order to grow properly.

I don't know why ducklings or goslings would die if turned upside down. I imagine it would be a combination of stress, and perhaps difficulty in breathing? Of course, in the egg, they do not use their lungs to breathe.