In Chapter D.7 they describe: "The complex reflection in water is interpreted by the network as a distant mountain, therefore the water surface is broken."

This is really interesting to me because the model would have to encode the reflection as both the depth of the reflecting surface (for texture, scattering etc) as well as the "real depth" of the reflected object. The examples in Figure 11 and 12 already look amazing.

Long tail problems indeed.