Closed captioning isn't always right, though. I don't believe it comes from official souses, either does it? I don't have any solid examples to show you, but I have seen mistakes in the closed captions before. This could be one of them.
I also thought that perhaps there is a missing scene in this episode. Like we all know, there is so much *important* stuff going on in this one that there may not have been room enough for an Astrid scene with Roscoe. Maybe there was a conversation between them when she brought the strawberry ice cream back to the lab? They could have discussed something from which the name Kelly, Kali, or whatever appeared.
Whatever the case, he doesn't call her by her name. That's for sure. Whatever the reasoning or meaning behind it, I believe she reacts with a very friendly, affectionate sort of smile. I get the feeling that she simply ignores all the silly names that Walter calls her, but this one seemed a little different to me, like it had more meaning for her. Any one else?
On another note, I too heard Kali at first. I had to think on it and then thought he said Kelly. On other viewings I heard Kelly at first... and then on another viewing (I wasn't paying much attention, I was talking with a friend) I thought I heard Kali again. Could it be Cali? Short for California? Maybe they had a discussion about when they were kids or something while talking over ice cream.
Oh and I'm looking for names that sound like the above... This is kinda interesting about the name 'Kallista':
And Kali, the goddess of Time and Change; The figure of Kali conveys death, destruction, and the consuming aspects of reality. As such, she is also a "forbidden thing", or even death itself,etc.:
Totally no clue whether or not there indeed *IS* deeper meaning in the funky name Roscoe gave Astrid in this episode, but it is rather interesting looking at these other possibilities. I especially like the mythology behind the Hindi goddess Kali. I'm done editing this post for a while. lol