The too-bright lights on the flag are very distracting and inconsistent with the rest of the image.

You additionally have the flag lit too strongly from the top, while the rest of your scene is being lit with a far softer light source from the RH side...The spyglass is placed within a shadow, and should not be showing any real highlights at all...

All the problems you found seem to be based on PhotoShop ideas. This scene is lit with infinite lights which determine light levels and shadows automatically. It's a very intelligent program which would not mess up the things you suggest. With the ambient moon light and a single background light, as if from the ships rear, this is accurate. The too bright highlights you talk about come from part of the tutorial which I kept in so as to show a new feature I learned in c4d.

The moon reflection doesn't seem so real to me, the rest looks great. I like the highlights on the flag, good luck!