There's a whole thread about it, and we knew about it before Zarate signed. He is an Argentinian who has opted to play for Chile. A lot of Chilean players don't like it, and Vargas has been especially vocal, presumably because they are in competition for a place. Mind you, neither will be playing for Chile if they can't get a kick for QPR.
Beth has put a thread up implying that both Zarate and Vargas were injured. This must have happened in training on Friday, as CR didn't say there were any fresh injuries in his presser. The press team usually put out a release concerning these things when there are a lot of questions being asked on forums. Nothing yet I presume.
I don't know what the facts are here, but I do think the club is developing a worrying habit of being 'economical with the truth'. The rubbish about Redknapp's 'resignation', the misleading way the accounts were presented, the obvious season long injuries to Taarabt. I find it easy to ignore propaganda, even when it is designed to keep people calm.