Robin says she never played any team sports. She says in High School she played tennis because she liked being on her own. However in Season 4, Episode 6 (Happily Ever After) Robin's Dad catches her kissing her hockey team mate.
As Robin and Mike pass the sundae back and forth, the cherry on top keeps appearing and disappearing.
Jeremy Gabriel's character is clearly named "Mike"; however the ending credits show "Mark".
Ted says he doesn't want to leave the party on the roof to go to the bathroom because, "...there's a huge line. I don't want to miss the slutty pumpkin". Ted lives in the building and he isn't hosting the party. He could run to the restroom in his apartment and get right back to the party.