Continuity mistake: When Barney is in the Professor's office, we see the professor put a red pen down on her desk and her hands are then empty. In the next shot, she suddenly has a blue pen in her hand.
Continuity mistake: When the gang are drinking a toast to Ted at the end of the episode, Robin's glass of champagne moves from her left to her right hand instantly when the camera angle changes.
Continuity mistake: When Lily, Ted and Robin are at the bar discussing Ted's building design, Lily's drink keeps moving between shots. Sometimes it is in her hand lifted towards her mouth, whilst in other shots it sits on the table.
Chosen answer: In a flash forward scene in Season 8, it shows him with his first born: a daughter.
XIII