Well, someone remarked earlier in the thread (I think it was this thread) that we'd never seen a clone impersonation that didn't involve Sarah as either the faker or the fakee, but now we have, with Cosima press-ganged into imitating Alison. And now we know why it's best left to the con-artist sister. Although Cos did have a moment at the podium where she mimicked Alison's cheerful expression pretty well.
And it seemed the show was kind of metatextually acknowledging their own visual shortcut that "bangs = Alison." All Felix had to do was stick fake bangs under Cosima's hat and boom (or bang), everyone accepted her as Alison.
Still, I found this one a bit too sitcommy, especially with the gag of the swapped envelopes. The Hendrixes are so organized all the time -- wouldn't Alison have insisted on clearly labeling both envelopes? I mean, not with "DRUG MONEY" emblazoned on one, but maybe color-coded masking tape or something.
My favorite visual gag, if it was a gag, was that shot where Siobhan and Helena were sitting opposite each other with Sarah behind them at the bar. The classic, simple split-screen setup would be to have the two Maslany characters on opposite halves of the screen -- Sarah behind Siobhan on one side and Helena alone on the other. Instead, they had Sarah behind Helena on one side and Siobhan alone on the other. It's such a perfect subversion of the old split-screen doubling-shot cliche that I have to believe they did it on purpose, just to show off. (Although there were a couple of less convincing composites with Cosima and Alison in the bathroom, when Cosima handed Alison the packet and hat and then when she walked out.)