Thomas Lennon's character, Klaus, suggests that they watch the German version of The Odd Couple in this episode. Lennon was in the remake of The Odd Couple that aired shortly afterward.
Robin has a TV in her bedroom so she can see herself on the news broadcast when in bed with Nick. In the episode "Moving Day" from season 2 she is against having a TV in the bedroom when Ted is moving in though she may have changed her mind and decided to put a tv in the bedroom.
Last appearance of Tugboat the dog.
When the four couples are standing in the conference room with the guys on one side of the table and the girls on the other, the order of both groups is such that each person is in the same order as their respective partner.