Blender Cycles Freestyle Line Breaking

I’m trying to make a short 5 minute toon shaded starship scene with Blender Cycles. The ship(s) in the scene also have a toon outline created by two line sets, one thinner one set to only render on creases and edge marks and one thicker one set to only render on object contours. It looks good and like the way I want it to be, but when I render an animation (camera flyby) I notice that on some frames certain lines break. You can see that here:

That looks pretty ugly. Is there any way this can be avoided or at least greatly minimized? Here’s the scene’s .blend file:

Nobody has a solution?