In the season finale of season 1, Mozzie states "I don't wanna end my days in some underground prison adopting cockroaches as pets". Willie Garson's character Stanley Nussbaum in Fortress 2 (2000) was a mentally challenged inmate who had a cockroach for a pet.
Charles Dickens references: In the episode "Upper West Side story", where the class is studying "A Tale of Two Cities," Mozzie introduces himself to Evan as Professor Magwitch. Mozzie also often uses the alias "Havisham." Both are names of characters in Great Expectations.
In Season 4 Alex is staying at the Athenian hotel on 10th Avenue. This was actually filmed inside SIXTY LES, a hotel near the corner of 1st and 1st. There is an art connection here too as the pool at SIXTY LES has a portrait of Andy Warhol in the bottom!
In Season 5, Diana decides to get pregnant via sperm donor and be a single mother. In real life, Marsha Thomason was pregnant by her husband, Craig Sykes. The show decided to write in Thomason's pregnancy instead of making Diana disappear.