In the beginning of the episode, Ted states that he has walked into very strange stuff in his room over the years. When the goat is shown, the date below says 6 May, while he states in an earlier episode that the thing with the goat happened on his 31st birthday, which is on April the 25th
Ted's underwear is visible in the scene where he is practicing poses for his Naked man. You can clearly see it left of the lamp which is supposed to cover his body.
When Lily is making her list of the reasons to have sex, she takes the cap off her pen and twice.