Kevin Connolly had actually retired from acting when show creators first approached about doing the show. It wasn't until he was informed the part of Eric had been written specifically for him that he decided to take part.
It is mentioned several times throughout the show, that Jake Gyllenhaal has taken over the role that Vince had in "Aquaman" in its sequel. This refers to Gyllenhal almost taking over the role of Spider-Man from Tobey Maguire in the sequel (Spider-Man 2 (2004)) after Maguire suffered from a back injury and almost became unavailable to perform the required stunts for the movie. It is also worth noting that "Aquaman" is directed by James Cameron, who was attached to direct Spider-Man (2002) for a long time before Sam Raimi was hired.
In season 4, Vincent stars in the fictional film "Medellin." A trailer was created for the film (which can be seen in the DVD set), and at the end of the trailer is the Internet link "www.medellinthefilm.com", which is an actual website created for and about the fictional film. It includes the trailer, stills, an interview with Vincent Chase, and a synopsis for the film.
Throughout the show, Ari's wife is always referred to as either Mrs. Ari or Mrs. Gold, or pet names like "honey, sweetie" by Ari. It isn't until the sixth episode of the last season that Bobby Flay addresses her as Melissa.
In season 5, Ari Gold calls up 'his college roommate' Peter Berg to try and talk him into directing 'Smoke Jumpers'. In reality, Ari Emanuel's roommate at Macalester College in Minnesota was Peter Berg, according to The New York Times (June 10, 2009). Peter Berg is also represented by Ari Emanuel.
"Medellin" and its bad reception by critics and audience has a lot of similarities to Southland Tales (2006). Both movies were big projects directed by directors (Billy Walsh and Richard Kelly), who had a huge success with an indie-flick (Queens Boulevard and Donnie Darko (2001)) that had a huge fanbases. Both movies were first screened at Cannes and a huge buzz was created about them. After they were screened, they both received bad reviews (Southland Tales (2006) scored the lowest reviews for the 2006 Cannes Film Festival, averaging 1.1 out of 5) and bad audience reaction. Additionally, Southland Tales (2006) went straight-to-dvd in many countries, just like "Medellin".
Ari Gold's "Let's hug it out, bitch" was ranked #6 in TV Guide's list of "TV's 20 Top Catchphrases" (21-27 August 2005 issue). Creator John Koch claims that he doesn't know where the line originated. In one of Piven's previous TV shows, Cupid (1998), his character is seen in a limousine yelling, "That's right good citizens, it's International Hug a Stranger Day! It's time to hug it out, you little freak!"
In the series Vince was at one point attached to star as Pablo Escobar in Medellin but ultimately loses the role to Benicio Del Toro; in reality, Del Toro starred as Escobar in Escobar: Paradise Lost (2014).
The character of Billy Walsh is mainly based on one of show's writers Rob Weiss and director Vincent Gallo. The story of Medellin getting trashed in Cannes Film Festival was loosely based on Gallo's highly criticized movie The Brown Bunny.
The apartment building used as Drama's home in season four is, in real life, home to Ron Jeremy. On filming days, Jeremy would visit the set, a few floors down and many times fell asleep in video village.
During a US Comedy Arts Festival panel discussion, host 'Elvis Mitchell' asks series creator Doug Ellin about characters based on actual people. Doug states that "Billy Walsh" is based on executive producer Rob Weiss who directed only one film Amongst Friends (1993). When asked about "Harvey Weingard" being based on Harvey Weinstein, Doug appears to be uneasy and says: "I thought we weren't gonna talk about this." Then regarding the actor playing Weingard - Maury Chaykin - Doug adds: "I don't know who he's basing that on."