The improv comedian with the newsboy-style cap and in the red, flannel shirt is the same guy who BoJack vomits on in the series premiere. He also falls into the open floor at the Halloween store Todd and Mr. Peanutbutter open. In S3E10 he is at BoJack's party, eating cotton candy.
Diane wears a commemorative shirt from her failed surprise birthday party in "After the Party" for the duration of this episode.
The painting in Abe's dining room is a spoof of Manet's Olympia.
When Bojack and Abe are talking near the catering table, a woman walks behind them with a shirt that reads, 'Vintage Rock Band T-shirt,' but it's written backwards.