In the pictures of Robin and Barney in the storage at the end of the episode, Cobie Smulders had short hair. While Robin and Barney were dating she had long hair.
When Barney is telling the story about him dating Robin, he says Robin moved to Brazil; when, in fact, she moved to Argentina.
When Ted realizes he left the keys for the car in Victoria's dressing room, the camera pans out from the windshield and you can see that the daytime running lights are on, meaning a key must be in the ignition.
While Barney is telling Quinn the story of how he and Robin began dating, he says that Ted got hit by a bus, when, in fact, it was Barney himself who was hit by the bus. Ted was also in an accident that same day, but he was instead hit by another car while sitting in a taxi.