In the flashback after Marshall and Lily's wedding his hair in the middle is just growing back after he shaved it with the clippers.
In the flashback scene, when Ted and Marshall are dressed as a wedding present and a note, after marshal moves away, we can see Ted move aside to reveal the Slutty Plumkin who was standing right behind him drinking her signature cocktail
When Marshall dressed up as the wedding gift and went to the bar and asked Lily why Ted wasn't getting it when referring to Marshall's wedding gift, she said " I don't know, why haven't you got the message to dress up as a pregnant teenager, home skillet?" which was a direct reference to the movie Juno (2007) in which Lily was dressed up as Paulie Bleeker played by Michael Cera in the movie.
Ranjit's appearance in this episode of wearing a baseball cap, sunglasses, and headphones is a nod to poker champion Phil Hellmuth.