As far as I know with these checks, as long as you haven't intentionally tried to mislead the adcom, you should be fine.
If the date you listed a position is a few weeks off from when HR said you started, that probably isn't going to kill anyone. But if you said you were a business unit head, but then the background checkers find out you were just an assistant to the assistant to the business unit head, that's probably going to send you to the guillotine.
Most schools have been secretive about which schools do or do not do these checks after one puts down the deposit. However, even for schools that don't do these background checks, nothing prevents them from verifying your information between the time you officially apply and the time they admit you either, because it is definitely possible that they did.