Animation with unintentional black boxes I'm making an Animation with a Motion Track. In my preview render everything is fine, but when I render my scene in png there are black boxes in some pictures.

At the beginning of the animation these dots (showing the cities) appear. After that the lines move towards the city Höxter. At the end a street sign is falling on the position where all lines are ending.

These black boxes just appear when the second animation is running. I don't have any other meshes in my scene that could create these black boxes or cast shadows on the map.

How can I fix it?

 

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Heres the blend file:
I downloaded my download file now, because user3800527 (thanks to you) told me, that its working on his pc. Now its working and there are no black boxes anymore. I can't tell exactly what the problem was. Maybe it just was a problem of blender.