I didn't like this episode much, I thought the plot was weak, the wedding side story was very unrealistic; I mean who is that girl?! She just appeared out of nowhere after years of separation and Alan's throwing her a wedding at his place ... Charlie's place!! Didn't make sense.
The main plot wasn't that good either, they got the chain of custody all wrong, why in the world would Homeland Security let the FBI handle such a case?!
It also looked as though the math was forced into the plot, it was logical but it "looked" unnecessary.
Aside from that, the rest was fine, the humor was ok, I liked the personal interaction between Don and Charlie, after all, personal interactions are the this show's best feature.