the tub will no longer fills and the thing on the top of the house will not drain those are the only two things i have noticed not working, i have yet to buy the 6000 and the 20000 dollar upgrades
from what i've seen the only upgrades that work are the three that cost 100. everything else pretty much doesn't work. the fridge upgrade to make ice for you only works until you quit and reload the game. i have no idea what the other building upgrades will do if they do anything at all. documentation is honestly kind of sparce