Few would accuse Teen Titans Go! of being a subtle show, yet the new feature film based on it, Teen Titans Go! To the Movies, included a surprisingly sly recurring joke about Henry Cavill's mustache. The original television series is famous for the many Easter eggs and sight gags it works into its backgrounds and the movie continues this tradition, with one mock movie poster depicting Henry Cavill and his mustache showing up several times over the course of the movie.
Henry Cavill's mustache (or lack thereof) has become something of a symbol of everything fans felt was wrong with the Justice League movie. The reshoots for the film were scheduled during the same span of time that Cavill was filming Mission Impossible - Fallout, which, perhaps not coincidentally, opened the same weekend as Teen Titans Go! To The Movies in the United States. Cavill had grown a mustache for his role in the film and his contract forbid his shaving it. After Paramount refused to let Cavill shave and just wear a false mustache in their movie, Warner Bros. was forced to use CGI that most felt was rushed and unconvincing, in an effort to try and make Superman look clean-shaven in Justice League.
Related: Henry Cavill's Mustache Explained
Teen Titans Go! To The Movies makes reference to this with a poster of a mustached man with Superman's trademark spit-curl that bears a striking resemblance to Henry Cavill. The poster first appears outside the movie theater where the Teen Titans crash the premiere of Batman's new solo film, Batman Again. It shows up a second time on the side of a building when the Titans visit the Warner Bros. studio lot in order to ask for their own superhero movie. The poster shows up one final time, alongside Superman himself, during a climactic chase scene near the end of the movie.
Seemingly even this was not enough to make the point, however, and there is yet another poster which makes fun of Cavill's mustache. This joke is delivered in the form of a poster for a Detective Chimp solo movie (for those unfamiliar with the character, he's a talking chimp who is also a detective, and currently a member of Justice League Dark). The full title of the movie is Detective Chimp and the Case of the Missing Mustache, with a Superman S-shield in place of the "S" in "Mustache."
While it may seem odd that Warner Bros. would allow one of their movies to make fun of one of their biggest blunders in recent memory, Teen Titans Go! has a long record of meta-humor, and the bad CGI mustache cover-job is the perfect target for that brand of comedy. Besides, with Deadpool 2 having already made fun of the CGI used to erase Henry Cavill's mustache, maybe it was time for the studio to try and get in on the joke themselves.