there's no doubt that the dc extended universe features some of the darkest superhero films in recent memory, in no small part due to zack snyder's take on the superhero genre, which began with man of steel, featuring a the darkest depiction of superman we've ever had on film. in batman v superman: dawn of justice, we got an even darker hero in batman, who charged into the seedy underworld of gotham like a shadowy monster, murdering and branding criminals who stood in his way. so you can probably agree that neither of these heroes are exactly "kid-friendly."
these films, combined with the recently released, and far more kid-friendly wonder woman, have now culminated in justice league, which is one of the dceu's lighter entries, but is it light enough to be considered appropriate for children?
despite the film's less dark tone, the film is still undoubtedly darker and more mature than parents might have hoped. one of the more obvious reasons for this is the inclusion of adult-themed jokes which riddle the film. take for example the scene in which lois lane reminisces about clark with martha kent at the daily planet. in that scene, martha tries to compliment lois by telling her how clark used to call her the "hungriest journalist" he knew. martha accidentally misquotes clark, calling lois the "thirstiest" clark had ever met -- "thirsty" being a euphemism for someone who is desperate for attention of a sexual nature.
you could argue that jokes like that are still quite tame. after all, it's not so different from some of the more adult-themed jokes in our superhero cartoons. the ones that completely went over our heads when we were kids? the thing is, kids aren't as oblivious nowadays. they have the internet in the palm of their hands, where the adult world has no secrets and little jokes like that are more readily picked up on and understood by young minds. it's one of the reasons modern superhero films are able to sneak the odd curse word into a few scenes, something justice league does quite a lot.
of course, the film isn't not all gritty atmosphere and adult jokes. our favorite dc heroes are, for the most part, everything we'd want in role models for our kids. wonder woman is as strong and inspiring as ever, the flash as the comic relief is funny while maintaining a welcome innocence, aquaman showcases all the bravado you might expect, but avoids doing anything dark, like committing homicide in the name of justice... well, at least not against anything that bleeds. finally, there's superman, bearing the symbol of hope on his chest. he's back, and he's much more lighthearted and heroic than previous iterations, so you won't need to worry about your kids seeing the man of steel snap more necks.