It looks as if the frame edge of the Enterprise-D
elements ends before the frame edge of the background elements.
An easy fix for that would have been to reposition the Enterprise-D elements further to the right until the frame edges matched, or to stretch those same elements slightly to the horizontal until the edges met up.
On a standard def, CRT television, you probably would have never seen this, because the overscan of the picture tube would have masked it off. In high def, where the entire frame is clearly visible to the home viewer, this is inexcusable. Very sloppy.