Both Jeff and the Grifting 101 teacher say the phrase "Because the Internet" in the bar scene, which is a reference to Childish Gambino's (Donald Glover's) second solo album.
Professor DeSalvo is played by Matt Berry who starred in the English TV series The IT Crowd (2006) as Douglas Reynholm. Joel McHale, who plays Jeff, starred in the pilot episode of the American version of the series, which was canceled after the pilot.
When Professor DeSalvo opens the briefcase after meeting with Britta in the closet, you can see red tabs in the combination lock preventing the lock from being changed and indicating that this is a brand new briefcase. The first user usually removes these tabs before use.
The music during the opening scene is The Entertainer, the theme song of the movie The Sting (1973), which is about 2 grifters, Paul Newman and Robert Redford, creating a big con.