A picture during the song "Kyle and the Kids" shows the kids at Todd's theme park 'Disneyland' from Yesterdayland (2015).
The David Boreanaz bobbleheads strewn about Bojack's house when he returns home are a callback to the scam Princess Caroline and Todd ran in the first season.
The posters in Penny's room rare animalized versions of FKA twigs, Bon Iver, and Lana Del Rey. The other poster is of Fleet Foxes, a real band with no change to the name.
At 06:04 - The quote in the yearbook by Gandhi: "It's something unpredictable, But in the end is right, I hope you had the time of your life" is actually part of the lyrics to "Good Riddance," by Green Day.