Michael Stuhlbarg researched his role as Arnold Rothstein so thoroughly that the show's writers found that he knew more about Rothstein than they did, and they deferred to his judgment of the character.

After completing the first season, Anthony Laciura was contacted by relatives of Louis Kessel, the real life inspiration of his character Eddie Kessler, and offered to wear when filming the pocket watch that Nucky Johnson gave Kessel as a gift. "Eddie" is seen consulting the watch in the following seasons.

Paz de la Huerta was fired due to being intoxicated most of the time she arrived on-set. In a Vanity Fair interview, La Huerta revealed that Hollywood mogul Harvey Weinstein had raped her in 2010 while she was filming season one of Boardwalk Empire. This traumatic event fueled her subsequent depression and alcoholism during season two.

Terence Winter always phoned an actor or actress when the writers decided to kill his or her character off.

Co-Producer and Director Martin Scorsese encouraged improvisation on-set during the filming of his pilot episode, something that is typical of his directing style, but very rare on scripted television.

The real-life figure of Enoch "Nucky" Johnson served as the inspiration for "Nucky" Thompson. Johnson was a physically commanding man, both tall and heavyset, with a receding hairline. He was quite unlike Steve Buscemi, and resembled the character of Tony Soprano from The Sopranos (1999). Creator Terence Winter also wrote for The Sopranos (1999), and created the character "Nucky" Thompson with Buscemi in mind, partially to make a central figure differing largely from Tony Soprano.

1920s Atlantic City was re-created for this series in a set in Brooklyn, New York. Executive Producer and pilot Director Martin Scorsese was so exacting in accuracy that (for example) he insisted the planks on the boardwalk be of the same exact size as they were in Atlantic City at that time.

Many of the period recordings, featured in season one, can also be found on the compact disc "Whispering: Hits of 1920" released by the Naxos label in 2002.

Richard Harrow's unmasked disfigured face was entirely computer generated. Jack Huston remarked that it was accordingly more of a challenge to imagine half of his face missing when he was not wearing a mask. Huston also stuffed cotton into the left side of his mouth to affect his speech and jaw placement.

According to Timothy Van Patten, Martin Scorsese's involvement as an Executive Producer consisted of reading the scripts, watching the rough cuts, and making suggestions. Van Patten praised the notes Scorsese gave, because they are very precise and insightful.

The age difference between Gretchen Mol and Michael Pitt, who play mother and son, is nine years. (Mol's character, Gillian Darmody, became a mother at the age of thirteen.)

The real George Remus (played in the series by Glenn Fleshler) would also refer to himself in the third person.

Many of the characters surrounding "Nucky" Thompson, and all but the basics of Thompson's life, were fictionalized. Major exceptions were the infamous gangsters depicted (Al Capone, Johnny Torio, Lucky Luciano, Arnold Rothstein, and Meyer Lansky), who were based by the writers and actors to some extent on the real criminals' personalities and actions.

Alec Baldwin was considered for the role of "Nucky" Thompson.

The exterior set of the Ritz-Carlton Hotel set was built with the interior included, up to the elevator doors, so characters could be seen entering and exiting the hotel in unbroken shots.

Steve Buscemi claimed that a challenge of working in television for him as an actor is that he typically keeps track of what facial expressions are needed for a role, and by the end of the series, he was running out of faces for "Nucky".

Michael Shannon admitted that he was not happy working in television, in which the filming of his scenes was spread over six months, and he had little to no time for discussing the script, nor his character.

The character of Esther Randolph was based on a real person, Mabel Willebrandt, who served as Assistant Attorney General under Presidents Warren G. Harding and Calvin Coolidge.

Commodore Louis Kaestner's (Dabney Coleman's) parlor, where many scenes revolving around him take place, was the Collectors' Suite of the Alexander Hamilton U.S. Custom House in New York City.

Director Timothy Van Patten delighted in directing Steve Buscemi for fight scenes, since the two of them were both experienced wrestlers in school. Van Patten further observed that filming fight scenes is causes its own physical exhaustion for actors, due to the need to suppress their full strength.

The pilot episode was directed by Martin Scorsese and produced at a cost of $18 million.

The series was inspired by the book "Boardwalk Empire: The Birth, High Times, and Corruption of Atlantic City" by Nelson Johnson about historical criminal kingpin Enoch L. Johnson.

To promote the second season, which started on September 25, 2011, the producers paid the Metropolitan Transportation Authority $150,000 to decorate and operate a New York Transit Museum train of four retired New York City Subway Lo-V cars for each weekend in September 2011. The subway cars used were 5290, 5292 (both built in 1917), 5443, 5483 (both built in 1924). The train operated between noon and 6 p.m. and as an express between 96th Street and Times Square-42nd Street Subway on the IRT Broadway-Seventh Avenue Line. While the MTA runs "nostalgia trains" each year, this was the first time they had been used for an advertising tie-in.

Designed by John Dunn and tailored by Martin Greenfield, Boardwalk Empire's costumes were based on 1920s tailoring books from the Fashion Institute of Technology's research libraries and examples found at the Brooklyn Museum and the Met. The costumes have also been rented from the Daybreak Vintage Company located in Albany, NY which also exhibits at the Manhattan Vintage Clothing Show. Dunn's designs were meticulously detailed.

The series won the Golden Globe Award for Best Television Series - Drama in 2011 and two Screen Actors Guild Awards for Outstanding Performance by an Ensemble in a Drama Series in 2011 and 2012.

On its original airing, the pilot episode gained a 2.0/5 ratings share among adults aged 18-49 and garnered 4.81 million viewers.

Steve Buscemi is the only cast member to appear in every episode.

The soundtrack won the Grammy Award for Best Compilation Soundtrack for Visual Media at the 54th Grammy Awards.

The series received 57 Primetime Emmy Award nominations, including two for Outstanding Drama Series, winning 20.

Filming for the pilot took place at various locations in and around New York City in June 2009.

For marketing purposes, HBO sponsored an Atlantic City beautification project with the tag line "Compliments of Nucky Thompson" and paid for eastbound tolls into Atlantic City on the AC Expressway for the weekend of September 24, 2011.

The second-season premiere was watched by 2.91 million viewers, down 39% from the pilot and down 12% from its first-season finale.

Boardwalk Empire has received critical acclaim. For its first and second seasons, The American Film Institute named Boardwalk Empire one of the ten "best television programs of the year."

Boardwalk Empire received widespread critical acclaim, particularly for its visual style and basis on historical figures, as well as for Steve Buscemi's lead performance.

Christiane Seidel (Sigrid Mueller) & Erik LaRay Harvey (Dunn Purnsley) also worked together on three episodes of Godless (2017) as Martha & Elias respectively.

The music used for the opening titles is "Straight Up and Down" by The Brian Jonestown Massacre.

Boardwalk Empire Volume 1: Music from the HBO Original Series, featuring music from seasons 1 and 2, was released on September 13, 2011.

Many of the costumes from the show were bought by United-American Costume in Los Angeles in 2015.

The series premiered on September 19, 2010, and completed its five-season run on October 26, 2014.

In the opening credits the labels on the Canadian Whisky washing up in the surf is missspelled. In Canada there is no "e" in whisky. However, Irish Whiskey does indeed have an "e".

Michael Stuhlbarg (Arnold Rothstein) & Shea Whigham (Elias 'Eli' Thompson) also worked together on Fargo (2014) as Sy Feltz & Moe Dammick respectively.

The series is set in Atlantic City, New Jersey, during the Prohibition era.

During the first season, Steve Buscemi was told that Nucky's first wife, Mabel, was actually in an asylum, and not dead, as the character said to whoever asked. When Buscemi got the script for the episode in which Nucky tells Margaret the whole truth about Mabel's death, he talked to Terence Winter and asked him why Nucky was lying to Margaret when the scene had a confessional tone. Winter replied that the asylum storyline didn't work out, so Mabel was actually dead. The mortality rates in institutions at the turn of the century was fairly high, and being institutionalized was considered a death sentence.

Michael Shannon claimed that before he read the script for his final episode, he received a phone call from Terence Winter in which the cell phone reception was so poor he could only hear every other word Winter said. Nevertheless Shannon immediately responded, "I'm dead, right?"

Dabney Coleman underwent treatment for cancer while filming season two, necessitating the plot twist of Commodore Louis Kaestner suffering a stroke and becoming incapacitated for most of the season. The schedule was also changed so that the entire first week of production on the show was filming Coleman's scenes for multiple episodes. However, Terence Winter claims that the Commodore's eventual death had been according to plan, and had nothing to do with Coleman's illness.

Owen's (Charlie Cox's) death was going to be shot, but when an accident on-set prevented them from doing so, the producers decided to skip the idea and have him die off-screen, with the subsequent surprise when his corpse is delivered at the end of the episode.

According to Terrence Winter, it was always planned for Jimmy Darmody (Michael Pitt) to be killed by Nucky" Thompson (Steve Buscemi), as a final payoff to Jimmy's warning to Nucky in the pilot ("You can't be half a gangster, not anymore.") However, Winter did not expect to kill Jimmy off as early as the second season. In an Archive of American Television interview, Winter explained that early to midway through the second season, Winter realized that the way the season was going, with Jimmy and Nucky turned against each other for control of Atlantic City, he realized that the only way the season could end was Nucky killing Jimmy, and thus completing his transformation to full gangster. Despite the backlash by fans of the series over killing a popular character, Winter stated that the uproar made him "more convinced than ever that we did the right thing."

In the final episode during the scene where Luciano and lansky are explaining their plans for the future of the mob, one of the other mobsters at the table says "don't forget to pay your taxes". This is not only a view on al capones legal issues, but could also be a reference to Nucky Johnson, the real life version of Steve Buscemi's character. Johnson was also jailed for tax evasion.

Steve Buscemi and Michael Pitt are the only cast members that appeared in every episode that aired before their characters were killed off.