My feeling is, that the last line "can a submanifold of a flat manifold be curved" is a real eye-catching line. It will attract attention, then again there could also be an affirmative answer which is not too difficult. I think it is worth a try, but you should mention the rough idea "can a submanifold of a flat manifold be curved". On your thought of it being trivial : Provide the context you need to, and if need be insert the links on the vanishing of the Riemannian metric, you'll be ok.