Early in the season, Beyonce trips and breaks her leg on the sidewalk. When BoJack accepts his Golden Globe, Beyonce can be seen in the audience wearing a cast.
The wide shot at the end after Bojack gives an autograph features a pink poodle and a brown corgi in the left corner. These are the same dogs from BoJack Hates the Troops (2014) that discuss chocolate in the grocery store.
When BoJack yells, "Garfield!" it calls back to an earlier joke in which Todd points out similarities between Andrew Garfield and the cartoon character cat, Garfield. (Garfield the cat's owner, Jon Arbuckle would frequently yell his misbehaving cat's name in frustration.)
The prolonged section of young BoJack's letter to Secretariat wherein BoJack asks whether they get the joke is a callback to BoJack's similar habit of asking, "Get it?" after every joke he delivers as an adult comedian.
When Sarah Lynn brings Andrew Garfield lasagna in the hospital it calls back to an earlier scene in which Todd finds amusement in similarities between Andrew Garfield and Garfield the cartoon cat.