Peacemaker has featured quite a few references to the larger DC Universe, including mentions of Aquaman, Batman and Bat-Mite. The show's fourth episode, "The Choad Less Traveled," delivered a nod to another superhero, Matter-Eater Lad. For those who need an explanation, Matter-Eater Lad (real name Tenzil Kem) is a Legion of Superheroes member who first appeared in the pages of "Adventure Comics" #303 in 1962.
Kem is from Bismoll, a planet where all food became inedible at one point, which forced its population to evolve their digestive systems to consume pretty much all types of matter (including metal and rocks) in order to survive. As such, Matter-Eater Lad can eat almost anything that's a threat (like an asteroid). He can also break down the components of whatever he consumes, which comes in handy when discovering poisonous substances. Lastly, his ability grants him temporary super-speed.
Peacemaker's reference to the character came when Christopher Smith discussed Vigilante with Clemson Murn. At one point, Smith stated that whatever sense of normalcy he had was thrown out the window when he teamed up with Matter-Eater Lad, who, as he recalled, once ate an entire Wendy's (as in, the building, not the menu). The reference was funny, but as we recently learned, it also served as a fun (and likely unwitting) continuity connection to 2019's Shazam!
A fan on Twitter talking about Peacemaker's Matter-Eater Lad nod pointed out that Shazam! director David F. Sandberg once (probably jokingly) stated he would like to make a movie about the hero. The director replied with a shot from Shazam! of Freddy Freeman's notebook, which comes from a scene in which Freddy and Billy Batson figured out what the latter's godly abilities were. The notebook had a list of different powers they tested out, and, as Sandberg pointed out, one of those abilities was matter-eating:
With that (assuming there isn't another character in DC's film universe who's become famous for eating matter), we're guessing that Matter-Eater Lad is a pretty well-known character in the franchise. Admittedly, this isn't a game-changing reference, and, as mentioned above, Peacemaker having any sort of continuity follow-up to Shazam! was more than likely accidental.
Having said that, the DCEU has featured a few lore inconsistencies throughout its films, so it's fun to see this type of continuity detail (again, as insignificant and inconsequential as it may be) between a DCEU film and TV show. Now, all we need is an actual appearance from Matter-Eater Lad in the DCEU to have his references come full circle.