Warner Bros. and DC are spending big money to ensure that “Justice League” builds on the creative success of “Wonder Woman” instead of serving up a “Suicide Squad”-style disappointment.

The studio, which had no comment on the scheduling trouble, is spending approximately $25 million on extensive reshoots that have dragged on for roughly two months in London and Los Angeles, according to multiple insiders. Like “The Avengers,” “Justice League” centers on a group of superheroes who band together to save the world. The ensemble nature of the comic book movie, and the fact that its cast includes several of the most in-demand actors working in Hollywood today, is creating scheduling headaches that have prolonged the shooting.

It’s standard for big Hollywood movies to schedule a few weeks of pick-up work, but the cost and time allotted to the work on “Justice League” is raising some eyebrows. Reshoots, or additional photography, to use the preferred studio nomenclature, traditionally cost between $6 million and $10 million, and rarely have to juggle so many competing schedules. They typically last a week or two.

Though stars like Ben Affleck and Gal Gadot, who play Batman and Wonder Woman, aren’t working on any other projects at the moment, enabling them to be on call for the filming, other cast members such as Ezra Miller and Henry Cavill have been scrambling to accommodate the additional photography.

Miller is reprising his “Fantastic Beasts and Where to Find Them” role in the film’s sequel, which started filming earlier this summer. Sources indicate that since that is also a Warner Bros. property, scheduling has been easier. The studio has gone out of its way to make him available, but his growing role in the world of wizarding series has made it difficult for him to suit up as the Flash on the same days that other co-stars are available.

Cavill’s issues are even more thorny. “Justice League’s” Man of Steel had expected to be able to finish shooting the sixth “Mission: Impossible” film before needing to don Superman’s spandex again. That has not been the case, however, as the new scenes that are being shot have required him to jump back and forth from each production. Because of this, a mustache he grew for his character in the “Mission: Impossible” sequel will have to be digitally removed in post-production. Paramount, which is distributing the “Mission: Impossible” sequel, would not allow Cavill to shave the facial hair while production was taking place.

Then there is the question of crediting. Joss Whedon has now spent months overseeing the project, but he will not receive a co-directing credit, according to an insider. Whedon stepped in to handle the reshoots and finish the film this spring after director Zack Snyder publicly excused himself from the project, following his daughter’s suicide in March. Whedon won’t just be rewarded with a fat paycheck. He may also get a producing credit or a screenplay credit. There’s some precedent. Tony Gilroy, who stepped in for director Gareth Edwards to oversee reshoots for “Rogue One: A Star Wars Story,” earned a screenwriting credit.

A similar problem exists for the Han Solo spinoff film. Last month, Disney and Lucasfilm fired directors Phil Lord and Chris Miller and replaced them with Ron Howard. It’s unclear if Howard will receive sole credit for shooting the film or will share it with his two predecessors.

Sources say “Justice League” reshoots have been used to punch up the dialogue. Whedon, the director of “The Avengers,” is well respected for his ability to create memorably wry exchanges between his characters. The set pieces Snyder shot are said to be usable, but Whedon has been working on “connective tissue” that was needed to link sequences.

“Justice League” is spending the kind of time and money on reshoots that mid-budget films would have to shoot an entire movie. However, this is no longer an anomaly. Major studio movies have become so complicated and expensive, and are often key parts in sprawling franchises, that companies will spend lavishly, even late in the production, to ensure that audiences come out in force. “Rogue One: A Star Wars Story” and “World War Z” both had extensive reshoots, and went on to be commercially and critically successful. “Suicide Squad,” another DC film, also did a lot of extra filming with mixed results. The movie was a box office hit, but critics savaged the picture. Going forward, Warner Bros. has changed its greenlighting process. It will now factor weeks and millions of dollars of additional photography into the production budgets of its major comic book films, according to insiders. Other studios have made similar accommodations on their big-budget films.

The reports of re-shoots have alarmed some fans of the DC franchise. At San Diego Comic-Con last weekend, where sneak footage of the film earned a rock concert reception, the “Justice League” cast used its Hall H panel to downplay the extent of the additional photography.

“They’re brief if anything,” said Ray Fisher, who plays Cyborg. “Zack picked a great director to help clean up for us.”

Affleck also used the panel to shoot down a report that he was leaving the franchise.

“Batman is the coolest part in any universe — DC, Marvel,” he said. “It’s incredible.”