The floating can is because the can was "inside" basket. the plastic baskets have a weird trait that you can put things into them and then pick the basket up and the items will become "attached" to the basket. The same happened to me with a piece of paper. I took the basket and scooped the paper with the basket and it unfroze it. As for the falling through the map. That part of the base hasn't had any collision for a while. i think it's just meant to be a teaser for something to come or just an easter egg to people who are really looking around the base. And you can climb out of there (and a lot of other places) by double tapping space against the wall while already jumping, this causes you to climb over obstacles like that area and fences.