Hey, first of all thanks so much for playing! but I'm sorry you encountered so many issues.
That first one is very concerning, I'll work on fixing that immediately!
2 is the result of a bunch of fast optimisations that I quickly threw together to make sure it runs well on all systems, so those white squares are basically the skybox, but it seems I wasn't very thorough in checking every piece of the map so thanks for bringing these to my attention! it's unfortunately very easy to miss things when working on jam games.
3 is also similar but caused by Unreal's built in occlusion, I'm still working on a good way to fix this without taking a big performance hint, unfortunately the image of these white squares is just burned into my mind and I see it in every Unreal game now lol
4 is especially concerning, that'll require some investigating, but hopefully I can find the cause of that and get it fixed!
TL;DR thanks so much for playing and bringing these to my attention! I'll work on fixing these.