If Marvel like one thing it’s cameos. If it’s another thing they like, it’s easter eggs which are plentiful in their movies and TV shows. These easter eggs usually offer hints to where a story is going or lays the groundwork for future properties. In the TV series Agents of S.H.I.E.L.D. there have been references to previous Joss Whedon properties, other stories in the MCU, and teasers for things to come. It has had four seasons, going into its fifth, and each season has had a plethora of easter eggs. Next season the gang will be in space, which leaves plenty of room for Inhumans and Guardian of the Galaxy references.

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Now with Inhumans filling in until it premieres on ABC, Spider-Man: Homecoming, and The Defenders finally coming together over on Netflix, there’s sure to be plenty of material for easter eggs in its fifth season. There have been too many fun, little easter eggs to count in its tenure, but we collected a couple of our favorites from over the years and threw them into a list for your viewing pleasure. So without further ado, here are 15 easter eggs that you probably missed in the first four seasons of Agents of S.H.I.E.L.D.

15 DEATHLOK'S ORIGINAL LOOK

J. August Richards, an Angel alum, was brought into the series from episode one. At first he was purely a victim of Project Centipede, but he was eventually maneuvered to become the comic book character Deathlok. He never resembled his comic counterpart, despite his gradual upgrades throughout the series. Sadly, these upgrades only ever looked like cheap, plastic props on top of regular clothing, leaving fans disappointed.

There was, however, one instance where the audience got one good look at Peterson actually resembling his comic book counterpart. When we see him under an x-ray lens we can finally see all of the metal and cybernetics that the character of Deathlok is known for. Don’t get us wrong, we love Mike Peterson, we just want to actually see him look like Deathlok and less like a prop from a high school play.

14 DAREDEVIL

The biggest appeal of Agents of S.H.I.E.L.D., especially when it was first announced, was the potential for crossovers with other MCU properties. And yes, it has happened to an extent, but not to the extent that we were promised or as much as fans were hoping.

One would think S.H.I.E.L.D. would have found its way into the Netflix shows, especially when S.H.I.E.L.D. became a legitimate organization once more and when there is a man with indestructible skin running around New York City. We did, however, receive a brief nod to the events from Daredevil in the season three episode “Watchdogs”. Blink and you’ll miss the news crawl at the bottom of the screen mentioning some action in Hell’s Kitchen.

13 JOHNNY BLAZE

There was a lot of excitement when it was announced that Ghost Rider was going to be appearing in season four of Agents of S.H.I.E.L.D.. What came with his appearance? You guessed it: easter eggs. In a flashback scene a couple of characters are looking for the “Darkhold” in a basement of the “family home of the guy who killed the last person who had it.” In this basement we see a poster for the “Quentin Carnival” which is a memorable place for Ghost Rider fans. 

It’s where Johnny Blaze, fan-favorite Ghost Rider, spent his days as a stunt driver. Along with this poster we can see a dismantled motorcycle and a black, leather biker jacket. Sure, it could be any old biker within this universe, but not likely. That’s a clear nod to our favorite Spirit of Vengeance.

12 DOCTOR STRANGE CONNECTIONS

Magic can be a tricky thing to portray on-screen. Marvel did pretty well, all things considered, especially when they decided to jump into the realm of mysticism in the fourth season of Agents of S.H.I.E.L.D., not long after the release of Doctor Strange -- they even managed to maintain continuity. We’re specifically talking about Doctor Strange’s sling ring that allows him to fast-travel great distances.

More to the point, the circle that appears when someone creates a portal to a different location. We see this same animation when Ghost Rider, Robbie Reyes, uses his chain to create a portal to a different dimension. It’s a minor detail, but one worth noting to maintain some continuity between properties. It is “all connected” after all.

11 ROXXON OIL

The Roxxon Corporation is a corrupt corporation within the Marvel Universe and has had a presence in the MCU since the first Iron Man. You’ll have to really keep an eye open to spot it, but it’s there. Roxxon Oil made its most notable cameo in Iron Man 3 during the climactic battle where the Iron Legion laid siege to Aldrich Killian and his cronies. Well, it was inevitable that this Exxon analog would make its way to TV land.

It did so in season one of Agents of S.H.I.E.L.D. with the presence of their own gas station. While Roxxon has been fairly innocuous, they have been known to be on the wrong side of history in the comics. They went so far as to ally with Frost Giants. Frost Giants!

10 WITH GREAT RESPONSIBILITY

Perhaps one of Stan Lee’s most popular lines in the Marvel Universe is “With Great Power Comes Great Responsibility”. Even casual, non-comic book fans came to be familiar with this famous line when the spandex-clad wall-crawler hit the big screen in Sam Raimi’s first Spider-Man movie -- it's a line delivered to Peter Parker from his Uncle Ben before he met his untimely demise.

During the pilot episode of Agents of S.H.I.E.L.D., written by Joss Whedon, Skye tells Mike Peterson, the eventual Deathlok, “With great power comes…” and just when we think she’s going to finish the line, she goes off script with “A ton of weird crap that you are not prepared to deal with.” It’s a great easter egg delivered in classic Joss Whedon cleverness.

9 SHIELD 616

When it comes to the big two comic book publishers -- DC and Marvel -- there are a lot of universes. That’s why it’s called a multiverse, after all. DC typically get flack for having so many different universes within their multiverse, but Marvel takes the cake here. The primary universe that most people are familiar with is universe 616.

That’s where the X-Men we all love are from. That’s where the main bulk of storylines take place when you pick up a comic book, and Agents of S.H.I.E.L.D. made a subtle nod to this fact. The large operation center of a cargo plane that the team flies around in, The Bus, was designated “SHIELD 616”. A fun little easter egg for the hardcore fans.

8 COULSON LIVES

If you’ve only been watching the MCU movies, steering clear from the television shows they put out on multiple platforms, then you’re unaware that Coulson is alive alive or how he came back to life. Spoiler alert. His being alive in Agents of S.H.I.E.L.D. is a clear reference to all the times heroes, villains too, have come back from the dead in the comic books. It was even mentioned that the procedure was in place in the eventuality that one of the Avengers ever fell.

Every other death in the cinematic universe has been permanent for the most part. Not even Red Skull has reemerged as a big bad in a movie despite him having a simple explanation in deus ex tesseract. It’s only a shame Coulson hasn’t made another appearance in the movies since his “death” in The Avengers.

7 WHEDONVERSE

If you’ve seen the Serenity movie, then you saw Simon save his sister River from the clutches of “benevolent” Alliance. In doing so Simon used a cane of sorts that he slammed to the ground and a blast erupted around him, knocking all the Alliance agents unconscious. A similar object can be seen in the episode “0-8-4”.

Grant Ward comes running out of a temple with a spike that he slams to the ground, sending a pulse outward that knocks over the enemy soldiers. Of course a show created by Joss Whedon is going to throw in little references to his own past shows. It’s a real shame the writers forgot about this technology because it could have come in real handy in multiple later episodes.

6 MADAME HYDRA

In the second half of season four, the team is thrown into a virtual world not unlike the Matrix called The Framework. It was created by Dr. Radcliffe and commandeered by Ada, his not so friendly LMD. Within the Framework Hydra is alive and well, ruling the world with an iron fist, just as they always wanted. And who is in charge of Hydra? Ada.

In this world, however, she is known as Madame Hydra. She’s clearly not Viper -- the Madame Hydra -- readers of the comic books know, but one wouldn’t be able to tell by first glance because there is a striking resemblance between the counterparts. The reality of the Framework was a clever vehicle of bringing in comic book characters we might otherwise never see in the MCU.

5 SECRET INVASION

Skrulls replacing Marvel heroes

Early in season one of the show Fitz repeatedly said “Embrace change” or some variation like “Embrace the change”. This phrase doesn’t mean a whole lot on its own. Coming from Marvel, though, it means a lot to fans because the phrase “embrace change” was a phrase repeated throughout the “Secret Invasion” event from 2008.

In this comic book event the alien race of Skrulls took on the identity of Earth’s superheroes in an attempt to invade the planet. For a while, because Fitz said this phrase multiple times, fans thought he was a Skrull and this series was the vehicle being used to usher the Skrulls into the MCU. That is until Fitz finally said he hates change. It’s probably best a “Secret Invasion” storyline wasn’t used so early in the MCU.

4 JOURNEY INTO MYSTERY

It’s evident that the writers for Agents of S.H.I.E.L.D. are fans of placing phrases from Marvel comics, and other Marvel properties, into this series. It can be a bit forced at times, but we love them for trying to fit them in whenever they can anyway. One such phrase made an appearance early in season one when Agent Simmons asks Agent Ward, “Are you excited to be coming on our journey into mystery?”

Longtime fans will recognize Journey Into Mystery as the title of a comic that actually introduced Thor as a character in the Marvel Comics Universe. This was fitting since the team encountered a lot of Asgardian events in season one like the Thor: The Dark World crossover, Lady Sif coming to Earth, and more.

3 PRESIDENT ELLIS

Yes, even people can be easter eggs while simultaneously making a simple cameo. President Ellis making an appearance on Agents of S.H.I.E.L.D. is another way for the writers to show the audience that this show is absolutely within the MCU continuity. Too bad we would like to see some characters from this show on the big screen too. Maybe one day.

Ellis was previously in Iron Man 3 when he was being held hostage by Aldrich Killian. Other characters have made cameos on the show such as Nick Fury and Maria Hill. President Ellis has an added level of easter egg because he is named after the writer Warren Ellis who has been in the comic book business for a very long time. He’s had several acclaimed runs on Iron Man and The Astonishing X-Men along with much, much more.

2 SITWELL HAS A BOAT TO CATCH

Jasper Sitwell has been a part of the Marvel Cinematic Universe since Thor in 2011. He is a S.H.I.E.L.D. agent that is eventually revealed to be a Hydra sleeper agent in the 2014 movie Captain America: The Winter Soldier. Before that movie premiered he was in several episodes of Agents of S.H.I.E.LD.

In the episode titled “End of the Beginning” Agent Sitwell is ordered to report to the ship called the Lumerian Star. Which, if you have seen Captain America: The Winter Soldier, will recognize that as the ship on which Agent Sitwell is being held hostage until Captain America and his team take control. Sitwell is one of the only characters that had made multiple appearances on both the TV series and Marvel movies.

1 ENERGY SHIELD

When Mack amputated Coulson’s hand in season two, Coulson received much more than a cybernetic prosthetic hand. He received a hand with some nifty surprises.Within his new hand is the ability to deploy an energy shield. This is an easter egg that works on multiple levels. One, it is the director of S.H.I.E.L.D. actually using a shield. Two, it is well known that Coulson has a fascination with Captain America. And lastly, cap has actually used an energy on multiple occasions in the comics.

This might very well act as a prototype, especially since he no longer has his shield after the events of Civil War. We first see this shield deployed in season three’s “Singularity” episode when Coulson uses it to protect himself and Agent May from an explosion in an Inhuman’s home.

Which of these easter eggs is your favorite? Let us know in the comments!