>>36988
I'm not sure how much in the trailer, but I think there is more than what you wrote. It can be argued if it is about current or an existing society, or a model of a hypothetical society. There's some talk in the movie itself about it. A little bit naive I think.
There's an allegory of reincarnation there, but I don't think that goes anywhere further.
A couple of plot twist in there, no earth shattering ones, but still, they mostly based on the lack of information the inmates have, or the lies they (perhaps) tell.
Little action, while the whole movie is static, events perk up a bit.
Right now I'm thinking I rewatch, I might missed some tidbits.