The rightmost box is a shadow cast by what appears to be the lower corner of the left side of the guy's camo jacket. It appears to be sticking out slightly, and that's what makes the shadow cast on the guy to his right.
The shadow in the leftmost box is more complicated; part of it is the leftmost guy's face, producing a shadow on his left shoulder. Whether it continues onto the adjacent sailor or not isn't clear to me; the dark area on his clothing might just be a dark camo area that happens to line up with the shadow on the leftmost sailor's shoulder....