Re: What did hidden mist mean in 605?
1. When I read it, I thought the Mist nins meant "he" as in Kakashi, and by "getting them", Kakashi had killed Rin (meaning that they wanted her alive). He's always seen reminiscing about not being able to protect Rin, which probably meant he tried and fought the Mist nins and failed, meaning he had to resort to killing Rin to prevent them from getting her alive.
(1) On page 3 of 605, they two hidden mist guys said "Shit, he got us...After we worked so much to get it!" I'm trying to figure out what they meant by that, because they said this right after Kakashi killed Rin. I know that they were after Rin for an unknown reason, but are they talking about Kakashi? or something else? Then again, they said "it," you think they would've said "her" if they were talking about Rin...what who is HE and what was IT? Hmmm...
(2) Also, at bottom of page 3, Kakashi says Rin's name as he drops to his knee, and it looks like he's shaking, then his MS is revealed on page 4, and he faints on page 5. I'm guessing he was shaking because maybe he wan't in control of his body, which also might explain why he fainted later on page 5?? Not sure...
As for what it was, well, it could really be anything but it'd have to be something big for Kakashi to kill Rin. There's been some discussion on the stickied discussion/prediction thread about Rin being a jinchuuriki, and it could be that. It would explain the large force sent after Rin, and if I was going to make a wild guess, it could fill up the mysterious backstory involving Yagura and the Sanbi. While Kakashi's unconscious, I could see Obito taking Rin's body with him. When he returned to Madara, Madara could claim the Sanbi for himself and decide to seal it into Yagura, which would be very interesting because of how Yagura was taken under the influence of Tobi's Sharingan at some point in time. As a matter of fact, I wouldn't be surprised if Madara had organized the whole thing (with Yagura already being under his control and him being the one who sent Mist nins after Rin to lure Obito there).
2. Yeah, he fainted because of the shock/obvious mental fatigue. I don't think it's anything suspicious.