Generally the attempts at hard science fiction in this film were very impressive, as were the sociological aspects. I honestly found it difficult to find plot holes. The realistic treatment of time scales was a breath of fresh air in a genre filled with FTL magic. Through the many obstacles, most questions about science and technology were suitably answered. But the one thing I never heard mentioned was
why the ship never received nor transmitted one communication to or from Earth or Mars.
The poem does show these attempts:
we spread the call-sign Aniara wide
in glass-clear boundlessness, but picked up nothing
Though space-vibrations faithfully bore round
our proud Aniara’s last communiqué
The ending absolutely floored me, and explains why eventually this would be impossible. It seems that at some point it would allow some kind of plan to be developed.