The region free Ghostbusters game is about online but people that have got it before the release date are saying that this Regionfree game asks to update your console when you try to play the disc.

So whats this mystery update and will this update mess up my UK console if I import it legit when released in US?

Who cares if there is an update, download it. And no it wont mess up your console if you import a region rf game then update it.