Wow, this was an AMAZING episode! I actually have a headache from the tension (I think that's a good thing!)
I was so glad to see some family interaction; I've missed that in the last few weeks. Irina looked so awesome on her mission, it was really fun to see her and Jack working together.
The thing with Vaughn...I had no idea what it would be until he said it at the end, but it makes sense that he would be checking up on Irina. I'm glad he didn't find anything, though. Which brings me to my next point..
I TRULY hope that Irina has some larger motive in this. I just don't want to believe that she's really bad. If she was, why did she turn herself in in the first place? She could have met with Sloane without being in CIA custody, and she didn't have anything to do with the take-down of SD-6, so she wasn't helping in that capacity. I think she's still working to bring down Sloane, she's just doing it her own way because the CIA is incompetent. (Like Jack said, that's where Syd gets her stubborn nature from.) But I feel so sorry for Jack...If he isn't in on it, then he must feel betrayed again. How will he ever be able to trust her again after this?
Of course, I guess it's possible she really is bad, I just don't want to think about it. She did have a really "hungry" look on her face when she saw that Rambaldi manuscript, and the thing where she asked Jack how he could avoid being lured in by it.... But I just think the part where she thanked Jack for raising their daughter, and where she told Sydney she loved her rang too true to be faked. I think those were real moments.