Could have been so much better

Terrific premise ruined by them trying to do a dance between the world being destroyed and it somehow being part of the simulation/hallucination.

Clearly the 400 day video was pre-recorded. There is no way a group was waiting outside unless they imagined leaving the ship and if they did imagine it then the movie is complete trash. Using hallucination as a major plot vehicle is beyond terrible because then literally anything can happen and hey, it was all just a hallucination.

I completely discount it being a hallucination as such a weak plot device it isn't worth considering. If it was supposed to be a hallucination then I would say the movie is terrible.

Once you discount the hallucination and look at their dealings with the surviving locals it gets even more ridiculous. Granted they would be disoriented and not really sure what was going on, but there was too much tangible evidence the world was destroyed to continue to pretend it was part of the simulation.

In short they didnt want to commit to either scenario and as a result the movie wasnt good.