Unusual for a television show, Creator John Wells has a very strict policy of no scripts allowed on-set. The actors and actresses have to know their lines by heart.

A unique show trademark is the main character breaking the fourth wall at the episodes' beginnings, inquiring as to why the viewer supposedly did not view the previous episode, before recap flashbacks are shown (with unaired scenes).

Steve Howey, who plays Kev, spent the entire season three recovering from a torn Achilles' tendon.

Woody Harrelson was originally set to star, back when the show was to air on NBC, then HBO, and then Showtime, before dropping out after the success of Zombieland (2009).

This is an American remake of an English series, Shameless (2004). The UK counterpart (same title) is set on the Chatsworth council estate, a fictional borough in Manchester. It originally ran from 2004 to 2013 for eleven seasons, and 139 episodes.

With the renewal for season 10, it became the longest show in both episodes (122) and seasons of all of Showtime's history.

According to details written in the early script of the show's pilot episode, Fiona Gallagher was originally supposed to be very average-looking and overweight, with rattier clothes and messy blonde hair; a huge contrast from the slender, brunette beauty (Emmy Rossum).

The show goes to Chicago twice for a week to shoot exteriors, after filming every six episodes on Warner Brothers' sound stages.

The cigarette brand "Morley" is used in several episodes. This is the same fake brand from The X-Files (1993).

Allison Janney played Sheila Jackson in the original pilot, but when the producers decided to expand the role, Janney had to drop out, because she was a full-time regular on Mr. Sunshine (2011), so Joan Cusack was cast.

Each child, aside from Liam (Brenden Sims), identifies with the behavioral roles of children of alcoholics. There is the perfect child or the hero (Debs (Emma Kenney)). There is the rebel or the scapegoat (Carl (Ethan Cutkosky)). There is the clown or the mascot (Lip (Jeremy Allen White)). There is the lost child or the loner (Ian (Cameron Monaghan)), and there is the caretaker (Fiona (Emmy Rossum)).

The cast admits that sometimes the scripts and story lines are outrageous, even to them.

Ruby Modine (Sierra), who plays Lip (Jeremy Allen White)'s love interest in season seven, previously dated Cameron Monaghan (Ian, Lip's brother) in real life.

Mark Mylod directed the first episode of both Shameless shows, the English one, Shameless (2004), and its American remake.

During the show's third season, Emmy Rossum had the show's writers give Justin Chatwin a fake scene, in which he told his father he was gay. The crew members revealed it was a prank on camera. He played a gay son to a homophobic father on Weeds (2005).

Besides playing the leading role of Frank Gallagher, William H. Macy also portrayed Frank Gallagher's twin brother, Jerry.

Early in her career, Shanola Hampton guest-starred as a Pep Squad Pepette on Reba (2001) with Steve Howey. Ten years later, they play husband and wife on .Shameless (2011)

Justin Chatwin & Noel Fisher, both Canadians from the province of British Columbia, used to room together in LA when they first started acting.

William H. Macy is the only series regular to have ever written (in season two) and also direct (season five) an episode of the series.

Nearly every single episode features either nudity or sex.

Ed Lauter, who played the school guidance counselor (Dick Healy), got sick in season three. He died (on October 16, 2013, two weeks shy of his 75th birthday) of mesothelioma, after being diagnosed five months earlier. His final episode was Shameless: Survival of the Fittest (2013), season three, episode twelve.

Paul Abbott, who created the original English series, was originally against the idea of an American remake, fearing it would be stereotypically set in the South. He changed his mind, once John Wells told him it would take place in Chicago.

William H. Macy and Noel Fisher have the same birthday, March 13.

When Lip (Jeremy Allen White) goes to Miami, there is a clip from the movie Bad Boys II (2003) where a helicopter is chasing a boat.

William H. Macy was nominated for the 2018 Emmy Award in the Lead Actor in a Comedy Series category for his role as Frank Gallagher in Shameless (2011), but lost to Bill Hader from Barry (2018).

Justin Chatwin and Emmy Rossum have worked together before on the film: Dragonball Evolution (2009) as respectively Goku and Bulma.

Michael Patrick McGill, Cameron Richardson, Janet Varney, and Will Sasso all appeared in at least one episode of the HBO series Entourage (2004), which Mark Mylod also directed.

Fiona (Emmy Rossum)'s gag of shaking down Frank (William H. Macy) doesn't translate too well; in Europe and England coins are used up to the 5 euro/pound denomination so the coins made sense in the UK series because a dozen coins could be used as the equivalent of $30 - $40 bucks. However, in the U.S. a dozen coins at best could only add up to $3. (The reason dollar coins aren't considered is because dollar bills are more popular than coins especially at bars, dollar coins are also more common for tolls and metro cards, and finally because the coins where clearly nickles and quarters.

Jane Levy (who played Mandy in the first season) and Justin Chatwin (Steve/Jimmy) starred together in the 2015 film Bang Bang Baby (2014).

Steve Howey and Justin Chatwin starred together in the 2016 film, Unleashed (2016).

Ethan Cutkosky (Carl) asked to be written off for a few episodes at the end of season five, because he was going to start high school, and wanted to experience it properly. He was able to start like a normal teen.

Even though it was established that Veronica was almost barren, she actually got pregnant in season four, because Shanola Hampton got pregnant.

Despite being in almost every episode since season one, Joan Cusack is listed as a "special guest star" in the opening credits for the five seasons she worked on the show.

Originally, there was a scene in the season three finale where the Brazilians played hockey with Jimmy's head, a clear indication to the audience that the character had been killed. They even made a fake head after Justin Chatwin but chose not to show the scene, in case they changed their minds about killing the character. Creator Justin Chatwin said publicly that the character was dead, but ended up bringing Chatwin back for a few episodes to write him out of the show properly and wrap up his storyline with Fiona.

The "Patsy's Pies" restaurant, at which Fiona (Emmy Rossum) is shown working, is based on a real bar and grill called "Patsy's", located on Lincoln Avenue in Chicago, Illinois.

Two actresses have portrayed Mandy Milkovich. Jane Levy and Emma Greenwell.

Jane Levy played the role of Mandy Milkovich in season one, but was then re-cast with Emma Greenwell, when Levy took a leading role in ABC's Suburgatory (2011).

The coffin that Monica is buried in in the final episode of season 7 is seen in the background of season 1 episode 2 when the kids are searching for Frank.

Season 4 takes place only a week after the last episode of season 3, which occurs on the first day of Christmas break. This is evidenced by Fiona (Emmy Rossum) reminding Debbie (Emma Kenney) that Ian (Cameron Monaghan) has only been gone for a week. Yet a lot seems to have happened in only a week. Fiona is now dating her boss after Jimmy (Justin Chatwin) has been gone for 2 weeks. Veronica (Shanola Hampton)'s mom is showing her pregnancy at only 13 weeks, and Svetlana (Isidora Goreshter) is also quite along in her pregnancy. Lip (Jeremy Allen White) is at college and classes have started, even though the college should be on Christmas break too.

Season 4 starts with Fiona (Emmy Rossum) telling Carl (Ethan Cutkosky) not to get used to sleeping on the top bunk since Ian (Cameron Monaghan) is coming back, but Ian always slept on the regular bed. Lip (Jeremy Allen White) slept on the top bunk until he got his own room in Season 3.

In season 5, after Fiona married Gus, she wears an engagement ring on her right hand, while Gus wears his on his left.

Kevin (Steve Howey)'s wife Cheryl, played by Cameron Richardson, shows up season 3 episode 3, Shameless: May I Trim Your Hedges? (2013). They make a reference to the Carlisle home. These 2 starred together in the 2004 movie Supercross (2005). In that movie Kevin's characters last name was Carlisle...