We all know Ted's relationship with Karen is marked by her cheating on him - in the episode where he finds out Lily was manipulating his relationships, when Karen finds Robin's earring, as a defense Ted even says "you've cheated on me like a million times"
But I never noticed before, Ted cheated on Karen first, at the freshman orientation party!
In the episode that introduces Karen, Ted says Karen would always come to visit him at college and then cheat on him.
That means those would have to be after the Freshman orientation party, when Ted kissed someone and then admitted it to Karen.
This isn't super significant but it changes my view of Ted and Karen's relationship a little bit.