Just how many times have Marvel movies and TV shows referenced DC's superheroes? Over in the comics, there's a rich tradition of each publisher subtly referencing the other. These are partly just Easter eggs for the readers, but they're also because writers and artists tend to jump between the two companies. One of the more amusing recent examples was in February this year, when artist Mike Deodato, Jr. subtly referenced DC's Captain Marvel as though he's part of the Marvel multiverse.
The movies and TV shows, however, are a lot more cautious and careful about referencing one another's properties. There are exceptions; Fox's Deadpool 2 was meta-aware, and made several brilliant puns about both the MCU and the DCEU. But, in general, the various superhero cinematic universes don't like to acknowledge one another's existence...
Which makes the handful of references all the more interesting. Here, we'll collect all the DC references that you can find in the Marvel Cinematic Universe. They're few-and-far-between, but they're certainly fun.
Curiously enough, the only explicit references in the canon to date have been two nods to the Super Friends animated TV series, which ran on ABC from 1973 to 1986. The term is used as a throwaway reference to various different team-ups; in Iron Man 3, for example, Happy Hogan refers to the Avengers as Iron Man's "super friends." There's a similar reference in The Defenders, with Luke quipping that he isn't looking for "super friends." Of course, the term is back in vogue now, in large part due to the musical episode of The Flash - which actually featured a song called "Super Friends."
Spider-Man: Homecoming's Interrogation Mode
There's one particularly entertaining reference in Spider-Man: Homecoming, when Peter activates the "Enhanced Interrogation Protocol." Hilariously, this leads to Spider-Man's voice being distorted electronically in a manner that's reminiscent of Christian Bale's voice in the Nolan Trilogy.
Luke Cage and Superman
Den of Geek has been highlighting a number of what they believe to be Superman references in the first two seasons of Luke Cage. These are a little more arguable, open to interpretation rather than being explicit. Den of Geek point out that the first trailer for Luke Cage's first season opened with Luke stopping a car with his bare hands, something they suggested this was subtly evocative of Action Comics #1, which featured Superman lifting a car.
Interestingly enough, Luke Cage has pretty much the same powerset as the original, Golden Age Superman, who also acted as something of a community champion a lot of the time. If Luke is indeed a vague parallel for a Golden Age Superman, then the scene in Season 2 where he emerges from the water may be a subtle nod to Superman's near-death from drowning in Superman: The Movie.