This is more an irritation than a fully fledged bug, but would be useful to iron out. If you rush a building you can then (accidentally) cancel it, without getting your money back. As the program treats it as not finished until you click next turn, it just deletes it like any other cancel. You then can't rush another building, because 'you've already rushed one building this turn'. To be honest I'd be tempted to include an 'are you sure' in more general to cancelling buildings that have started, as at the moment it is too easy to cancel buildings by clicking the wrong button.