While it didn't receive quite as negative a critical reception as fellow DC Extended Universe entries Batman v Superman: Dawn of Justice and Suicide Squad, Justice League did have its fair share of problems. One of the movie's issues was the poor CGI work done to hide Henry Cavill's mustache, which he'd grown for his role in Mission: Impossible - Fallout. Due to the Justice League reshoots coinciding with Fallout's principal photography, Cavill wasn't able to shave off the upper lip decoration, but even he couldn't have predicted how just a little facial hair would have affected such a major superhero movie. Cavill recalled:
I was slightly surprised. When we decided to go for the mustache, I certainly wasn't expecting all the events to unfold as they were going to unfold. I wasn't expecting Justice League reshoots to be as extensive as they were. When it came to that, it was one of those things where I'm in the middle of another movie, and to change my look for a movie that should have finished already becomes a real problem. And as you will see when the movie comes out, to have a fake mustache on would not have been a possibility. You'll think, 'Okay, yeah, a fake mustache would perhaps have been blown off in this situation.' Unfortunately, it led to much dismay when Justice League came out, but that's the nature of these things. You can't win every time.
Shortly after it was reported that Henry Cavill had to keep his mustache intact for the Justice League reshoots, Mission: Impossible - Fallout director Christopher McQuarrie stated that the only way a fake mustache would have worked for Cavill is if it was applied with a"liberal dose of staples." So unfortunately for Justice League, the mustache had to stay on when he reprised Superman, and the end result didn't look great. Following director Zack Snyder's departure from Justice League, Joss Whedon, who'd already been hired to rewrite part of the DC blockbuster, was selected to oversee the reshoots, and the movie went through some major retooling to the tune of a reported $25 million. Alas, while Superman did return to life during Justice League and helped Batman, Wonder Woman, Aquaman, Flash and Cyborg defeat Steppenwolf, it was obvious to many which of the Man of Steel's scenes were filmed during the reshoots and which were from the original shoot.
Henry Cavill also acknowledged in his interview with Empire that while it was a little silly to keep Superman out of the Justice League marketing materials given that it was common knowledge he was coming back, he also wanted there to still be a little mystery for the audience before they went to see the movie, so there wasn't necessarily anything wrong with keeping secrets. In any case, Superman is now back among the living in the DCEU and has resumed his superheroic career, and ideally whenever he next appears, Cavill won't have to worry about facial hair causing major problems.