Translation:There is egg in the mooncake.
Yes, as you may know, in the center of most mooncakes is an orange egg yolk "moon". So inside is better here. Just saying "in" suggests that eggs are an ingredient (they could be beaten in to the batter) but "inside" clarifies what is meant.
"There is egg in the mooncake" implies that there is an egg in the batter of the mooncake. "There is an egg in the mooncake" or "There is an egg inside the mooncake" implies that in the center of the cake is an egg.
I agree, we have a cultural and semantic issue here. My statement was "there is egg in Mooncake" implying ingredient. That was not accepted because I didn't use the word "the". Is there honestly a non nuanced way to say this where ingredient is not implied / style IE the egg yolk in the center?
"Mooncakes have an egg inside," or "Mooncakes have an egg yolk inside," or even better, "All mooncakes have an egg yolk in the center."
"There are eggs in mooncakes," seems acceptable, although I doubt if it quite says what is intended.
"There is egg in a mooncake" not accepted. Reported 22nd November 2018.
That's not really natural. It sounds like one cake of several has egg as an ingredient but we don't know which.
I got marked wrong because I put in "moon cake" instead of "mooncake." Reported!