Star Kirk Douglas, whose company, Bryna Films was producing “Spartacus,” was the one calling the shots on this classic gladiator movie, as far as the director was concerned. After two weeks of shooting, Douglas got the approval of the studio to replace Anthony Mann, an experienced director of Westerns, saying Mann had lost control and was letting co-star Peter Ustinov direct his own scenes.

Douglas brought in Stanley Kubrick, who had directed him in “Paths of Glory,” and the film ended up winning four Oscars as well as the Golden Globe for best drama. “Spartacus” was Universal Pictures’ highest-grossing film until “Airport” 10 years later.

“Bohemian Rhapsody” was already several months into production when director Bryan Singer failed to return to set after the Thanksgiving break. The studio temporarily halted production due to a “health matter” involving Singer — his mother was later revealed to have been ill — but reports swirled about Singer’s unreliability on set, verbal abuse and his alleged disagreements with star Rami Malek.

Dexter Fletcher, who was previously attached to the project, was brought in to replace Singer and finish the final third of the film. Though he wasn’t mentioned in promotional materials, Singer received a sole directorial credit, in line with DGA guidelines, and Fletcher was credited as executive producer. It became the highest-grossing musical biopic until “Michael” was released, and won four Oscars in addition to a best picture nomination.

“Justice League” is one of the most famous recent examples of a director swap. In 2017, Zack Snyder stepped away from the film during post-production to grieve with his family after his daughter took her own life. Joss Whedon, who five years earlier hit big directing Marvel’s “Avengers,” was brought in and made sweeping changes to the film. Allegations of misconduct followed, and the understandable outrage of Snyder fans eventually led to the 2021 release of “The Snyder Cut” of “Justice League,” which clocked in at just over four hours.

During a recent sit-down with Variety, Snyder said he’s never seen Whedon’s version of “Justice League,” given the hardships he and his family were experiencing at the time of release: “I’ve never seen it. There was a point when the movie was released that was a low point for me because the pile-on effect was so insane. Not only did I lose my daughter, but also they’ve released this version of the movie that I had nothing to do with and my name is on a movie that I didn’t make.”

The production of “The Island of Dr. Moreau” was an absolutely legendary debacle. Original director Richard Stanley had been developing his pet project for four years when New Line recruited Marlon Brando to star as mad scientist Dr. Moreau. New Line wanted Roman Polanski to direct, but Brando appreciated Stanley’s vision and the film lurched into production in Australia. Bruce Willis had already dropped out of the film, with Val Kilmer stepping in and immediately acting erratically, while Brando’s daughter died by suicide before principal photography began. Two days into production, while a hurricane raged across the region, co-star Rob Morrow quit, and one day later Stanley was fired by New Line.

Veteran director John Frankenheimer was brought in, though the tensions continued, with both Brando and Frankenheimer tangling with Kilmer. The film’s fired production staff later reported that Stanley returned to set in a dog-man costume and acted as an extra in the film he was fired from. The film flopped and swept the Razzie Awards nominations.

Father-and-son producer duo Alexander and Ilya Salkind made the bold choice in 1977 to film “Superman” and “Superman II” simultaneously, much to the chagrin of director Richard Donner. Tensions rose to such a boil that they decided to stop production on the sequel and focus on getting the first “Superman” in the can. “Superman II,” at that point, was mostly finished. After the first film dropped in 1978, Donner was pink-slipped and replaced by Richard Lester, who reshot most of “Superman II” so he could be credited as director.

In 1978, famed Variety columnist Army Archerd caught up with producer Pierre Spengler at a Christmas party. The French producer told Archerd that despite tensions on the first “Superman,” he was looking forward to collaborating with Donner on the sequel. Archerd then followed up with Donner, who told him of shooting the sequel with Spengler, “If he’s on it, I’m not.”

Brenda Chapman spent six years developing and writing the screenplay for “Brave,” which was based on her relationship with her daughter and featured Pixar’s first female protagonist. Chapman came on as Pixar’s first female director, only to be replaced by Mark Andrews due to “creative differences” with John Lasseter.

“I think it’s a really sad state. We’re in the 21st century and there are so few stories geared towards girls, told from a female point of view,” Chapman told the L.A. Times. “Brave” ended up winning the Oscar for best animated feature, with Chapman and Andrews credited as co-directors.

Phil Lord and Christopher Miller, the directors behind this year’s sci-fi box office smash “Project Hail Mary,” were originally set to direct “Solo: A Star Wars Story.” After a lengthy casting process, shooting began in January 2017, and by June 2017, Lord and Miller were out. Lucasfilm cited “creative differences” as the reason for the exit, and Ron Howard was brought in as a replacement with most of the movie already shot. It was later reported that Lucasfilm boss Kathleen Kennedy clashed with Lord and Miller over tonal issues and the loose shooting style they brought to what production considered an ironclad screenplay.

Hanging over all this behind-the-scenes drama was an ever-increasing production budget, which topped out at around $275 million. The movie only made $392 million worldwide, marking a major bomb for Disney and Lucasfilm.