In Aquaman, Arthur Curry drops Fight Club in a conversation with Mera while they are searching for an ancient Atlantean outpost in the Sahara desert. It means Jared Leto (Angel Face) exists in the DCEU, and he looks a hell lot like the Joker (without makeup). And the actor who played the mechanic (Holt McCallany) has a spitting image with the burglar Batman uses to lure a Parademon in Justice League (unless one considers this one Canon Discontinuity because of the director's cut).
Does Arthur Curry / Aquaman (Jason Momoa) ever get mistaken for the guy who portrayed Khal Drogo?
Field Marshal Douglas Haig (James Cosmo) looked like Lord Commander of the Night's Watch Jeor Mormont.
Ciarán Hinds again (the King-Beyond-the-Wall Mance Rayder), as he voiced Steppenwolf.
The reactionary terrorist leader "Black Clad Alpha" (Michael McElhatton) looks an awful lot like the guy who played Lord Roose Bolton.
Before turning into a monster, Waylon Jones / Killer Croc (Adewale Akinnuoye-Agbaje) looked like the actor who played the slaves merchant Malko, who wants to cut and sell Tyrion's genitals.
Francis Magee (Night's Watch recruiter Yoren) was the king of the men who helped repel Steppenwolf's first invasion of Earth in ancient times.
Oberyn Martell is a dead ringer to Maxwell Lord except for the latter's blond hair and clean-shaven visage.
The Rocky franchise exists in the DCEU with Billy-as-Shazam namely referring to it and using "Eye Of The Tiger" on purpose to show off his powers on the iconic stone steps before the entrance of the Philadelphia Museum of Art.
There's also the matter of Mortal Kombat vs. DC Universe which even featured Shazam (back when he was still Captain Marvel).
In SHAZAM!, a woman who got "kidnapped" by the Wizard Shazam mentions Harry Potter. Likewise, in Aquaman and the Lost Kingdom, Arthur compares Orm's prison to Azkaban. Assuming the movies exist:
A still from Wonder Woman 1984 has Diana / Wonder Woman looking at screens, one of which broadcasts Dallas. Hugh Maguire, who played Wayne Financial executive Jack O'Dwyer in Batman v Superman, played a character named Norm Crane in an episode of Dallas, and another named Goldman in five more episodes. He also appeared in two episodes of the Dallas spinoff series Knots Landing, as yet another character.
Parodied when Peacemaker rants off a list of people that Economos could've framed for a murder he committed (in lieu of framing Peacemaker's dad), which consists of various celebrities and fictional characters... including Freddie Stroma (Vigilante, who's in the room) and the show's writer/director James Gunn, to which Economos protests that neither of those are real people.
Said rant also confirms that the G.I. Joe franchise exist in the franchise. Assuming the filmseries also exists, then Saïd Taghmaoui played Abel Shaz / Breaker in G.I. Joe: The Rise of Cobra and Sameer in Wonder Woman while Dwayne Johnson played Marvin F. Hinton / Roadblock in G.I. Joe: Retaliation and also played as the titular character in Black Adam.
Vigilante mentions being a fan of Fargo at one point. The first season of that show featured Kevin O'Grady (Officer Johnson) as Sam Hess, while the second season featured Patrick Wilson (Orm Marius / Ocean Master) as Lou Solverson, and the third season featured David Thewlis (Ares) as V.M. Varga.
The Goonies - which was filmed around the time Clark was just a child - has Sloth, who wears a t-shirt with a Superman logo on it as a nod to the director'sothermovies.
Vig insults some white supremacists by saying they look like Sloth.
SHAZAM! Fury of the Gods: Billy (as Shazam) references The Fast and the Furious franchise while talking to Hespera. Hespera is played by Helen Mirren, who at the time of the trailer's release had already been in three Fast films as Queenie Shaw, plus Djimon Hounsou (the Wizard Shazam) as Mose Jakande. Additionally, Dwayne Johnson (Black Adam), John Cena (Peacemaker), Gal Gadot (Wonder Woman), Jim Parrack (Jonny Frost), Scott Eastwood (Lieutenant GQ Edwards), Michael Rooker (Savant), and Idris Elba (bloodsport) appear in the Fast and the Furious franchise as Luke Hobbs, Jakob Toretto, Gisele Yashar, Kenny Linder, Eric Reisner, Buddy, and Brixton Lore respectively. We might be generous and not count Jason Momoa (Aquaman) and Daniela Melchior (Ratcatcher II) in Fast X, which was still in production at the time.
