We already know that Mikoto has an icy reception toward the MISAKAs, but what I'd be really interested to see is her reaction to Last Order. We should be reasonably sure she doesn't know of her existence since she was only unbottled after the Accelerator incident closed. I think it would be very entertaining to see how she takes to a little version of herself that is essentially the queen bee of the remaining Sisters. It is also nice that the Sisters are beginning to develop individuality (like Tachikomas!) and one in particular disrespects Last Order.
What Touma should realize is that now he has seen Mikoto's mother. He should know by now that Mikoto looks nearly exactly like her, and from that, once Mikoto finally enters puberty (don't forget she is still a middle schooler!), she will start heading in that direction too. Look to the future Touma. I guess he still thinks she's pretty obnoxious and demanding though. Strange that he is more annoyed by Mikoto rather than a certain ward of his.
This indeed was one of the more entertaining episodes this season. It seems to be likely because we haven't had to listen to any of that self-righteous bullshit that has plagued so many of the other arcs.
I personally was the most amused to Accelerator's reaction to Loli-sensei, as well as Seiri's assault and Loli-sensei's reaction there.
(Note: I still strongly support Kanzaki x Touma despite the above paragraphs.)
edit: Does Maid Maika have any knowledge of her brother's magical abilities? She is not an esper, so I can't help but wonder if she has some knowledge of magic.