Ted: "Yes, Barney, your submissions were received and no, we will not be attending any parties in your pants."
And the evite with the actual picture of his pants! :)
When Lily leaves Marshall and she promises to return, I was totally thinking of Willow's "I will always find you." in the BtVS S5 finale. (It now occurs to me to think of River's "You gave up everything to find me; you found me broken..." in "Safe" [Firefly].)
Barney: "I don't want to be kissing Ranjit!"
Ranjit: "You don't know what you're missing!"
And I totally knew when Derek showed up and Ted left that Robin would keep their deal.
Oh, and I love how Maribeth totally sees (and is okay with) not only that Ted lurves Robin, but that Robin's into him as well.