Thanks for all replies.
Motion blur:
oops, I did forget to add that. Was always meant to be added in post, but I forgot.
Rendering errors:
Yes, there's a few. We struggled with them throughout. Oshyan you mention that these might be fixed in a final version?
So the new software addresses those issues? That would be cool!
I'm still considering adding a bird flying around (mainly to hide some errors).
But I may just leave it as is, with the exception of adding motion blur.
Render time was long: there's something like 1560 frames, rendered at 1024x576 resolution, and each taking between two and three hours.