The belt worn by Barney after he lies about having a threeway was first part of a storyline from the 3rd episode of the 3rd season, titled "Third Wheel".
One of the girls Barney meets in the bar calls him Neil (thinking he was Neil Armstrong) followed by the other one saying "That's not his real name". Barney Stinson is played by Neil Patrick Harris.
The pizza delivery man, is yet another Breaking Bad actor in this show. He played "Badger"