The personal check Bill receives from Holden for $350 is dated April 7, 1980, which confirms that at least episode 1 takes place in 1980.
Michael Cerveris (Ted Gunn, the new head of the Behavioral Science Unit) played The Observer opposite Anna Torv (Olivia Dunham) on Fringe (2008).
It can be confirmed that at least this episode takes place in the year 1980 because at Agent Smith's retirement party, it's stated that he has been an agent for 27 years beginning in the year 1953.
When Shepard informs Bill that he's retiring and passing the torch to Gunn, he mentions BSU's convictions in the Devier and Soult cases. The Soult case was actually the BARNWRIGHT case on the show. Soult was the real life case which it was based off of.
Andy Umberger describing a dead body may sound familiar. He also played the coroner, Malcolm Carruthers in the game, L.A. Noire (2011)