Paul Walter Hauser plays the underground villain Mole Man, who plays a minor — but important — role in “Fantastic Four.” After being quickly defeated by the heroes in the beginning of the movie, Mole Man (whose real name is Harvey Elder) develops a truce with Sue Storm and later opens up his underground world of Subterranea to house the surface dwellers during Galactus’ attack.

Latveria is the fictional homeland of Doctor Doom, the Fantastic Four’s nemesis who will be played by Robert Downey Jr. in “Avengers: Doomsday.” A quick scene in “First Steps” shows several delegates from foreign countries, but the representative from Latveria is conspicuously missing. There’s a nameplate for the country, but nobody is there. In the post-credits scene, though, we seen Doctor Doom himself — from behind, but it’s clear it’s him — ominously meeting Franklin Richards.

John Malkovich was originally set to play the Soviet scientist Red Ghost, but he was later cut from the movie. However, his name gets mentioned, and one of his Super-Apes is seen fighting Mister Fantastic in the opening. In the comics, Red Ghost experiments on a group of primates, gives them powers and dubs them his Super-Apes. An orangutan named Peotor briefly fights Mister Fantastic, and Red Ghost appears in the animated post-credits scene.

Giganto is an enormous monster, released by Mole Man, thats fights the Fantastic Four at the beginning of the movie in an homage to their iconic comic book cover. On the cover of the very first issue of “The Fantastic Four,” Giganto bursts out of the ground and attacks the team, exactly like the creature appears in the movie.

In the ’90s, there was a low-budget “Fantastic Four” movie that was shot and made for $1 million by producer Roger Corman, but it was allegedly so bad it was never released. It starred Alex Hyde-White as Mister Fantastic, Rebecca Staab as the Invisible Woman, Jay Underwood as the Human Torch and Michael Bailey Smith as the Thing. Now, the four actors get their chance to appear on the big screen. They all appear in the montage of citizens thanking the Fantastic Four in the opening of “First Steps.” Hyde-White and Staab also play TV journalists narrating the adventures of the team, and Underwood and Smith are saved by Human Torch at a power plant.

Every world in the multiverse gets a designated Earth to take place on, and “Fantastic Four: First Steps” is revealed to be on Earth-828 in the opening of the movie. The retro futuristic world is clearly different from the rest of the MCU, which takes place on Earth-616. At the end of the movie, Earth-828 is shown to be a reference to legendary Marvel comics artist Jack Kirby, whose birthday was Aug. 28, 1917 (or 8/28). Kirby co-created the Fantastic Four, the Avengers, the X-Men, Hulk, Iron Man, Thor and many more characters.

In the comics, young Franklin Richards is one of the most powerful beings in the universe. He’s a mutant with the power to reshape reality and has telekinetic abilities that rival the strongest heroes. Galactus, a supreme being himself, wants to free himself of his planet-devouring hunger and pass his cosmic power to Franklin, but the Fantastic Four save the newborn baby. Franklin appears bring his mother, Sue Storm, back to life, and is seen reading Charles Darwin at just four years old in the post-credits scene.

Yancy Street, the Thing’s old stomping grounds from the comics, gets a quick shoutout in the movie. The street is a reference to Delancey Street in Manhattan’s Lower East Side.

Several classic Fantastic Four villains from the comics get brief mentions in “First Steps.” One of them is Puppet Master, who can psychically control homemade puppets.

Diablo is an evil master of alchemy who gets mentioned in “First Steps.”

Despite the name, the villain Wizard possesses no magical abilities. However, he’s a magician with genius intellect who invents several powerful gadgets, and he gets mentioned in the movie.

The Mad Thinker is another evil genius who is referenced in “First Steps.” In the comics, he’s created several powerful robots, like Awesome Android and Quasimodo.

A giant, cosmic being who eats planets needs to get around the universe somehow, and that’s where Galactus’ Worldship comes in handy. Named Taa II, Galactus’s highly advanced ship travels around space and brings him to unlucky planets for him to devour.

Despite the name, Dragon Man is actually an android who was brought to life by Diablo to battle the Fantastic Four. The monster appears in the animated TV scene in the post-credits.