According to Zack Snyder, this version contains no shots filmed by Joss Whedon from the theatrical version of Justice League.
Despite directorial credits, Zack Snyder has never actually seen the theatrical cut of Justice League (2017). Reportedly, his wife Deborah Snyder and his good friend and executive producer Sir Christopher Nolan advised him to never see it, as it would "break his heart."
Victor Stone/Cyborg was originally described as the "heart of the movie" by Zack Snyder and Deborah Snyder, but Joss Whedon controversially cut most, if not all, of Cyborg's storyline for the theatrical version. Victor's plot line is restored in this version.
Confirmed in an interview by Deborah Snyder and Zack Snyder. The Snyder Cut only has about five minutes total of new shot added scenes with actors but there are over 2,000 new visual effects shots in the four-hour film.
This is not the first time Warner Bros. has released a director's cut under public pressure. In 1980, a similar issue surrounded after the release of Superman II (1980). Critics believed the film was lacking the superior tone of its predecessor. Original director Richard Donner was fired by the producers and was replaced with Richard Lester. Lester altered the film's pacing heavily and made it lighter in tone compared to the first film. Decades later in 2004, Lois Lane actress Margot Kidder said in an interview that a Richard Donner cut of Superman II exists. Following this, a fan petition started which caught the attention of Michael Thau, a film editor. He contacted Warner Bros. and proved the existence of the Donner cut. After Warner Bros. green-lit the release, Thau teamed up with Stuart Baird to reassemble the footage Donner shot during his involvement. Thau and Baird took some advice from Richard Donner himself. This marked the return of the original Superman (1978) composer John Williams by way of archived recordings. The final cut, which ran for 116 minutes (the theatrical version ran for 127 minutes), was released as Superman II: The Richard Donner Cut (1980) in November 2006, after the summer release of Superman Returns (2006).
Marc McClure: As Jerry, the police officer whom Lois gives coffee to at the Superman memorial. He played Jimmy Olsen in all four of Christopher Reeve's Superman films, as well as Supergirl (1984).
Carla Gugino: As the voice of the Kryptonian ship. She previously worked with Zack Snyder on Watchmen (2009) and Sucker Punch (2011). She also voiced the Kryptonian birthing device in Man of Steel (2013), and the ship in Batman v Superman: Dawn of Justice (2016).
Zack Snyder: Appears in the background as a customer of the coffee shop Lois Lane (Amy Adams) visits early on in the film.