If you're a Godzilla fan, you may have found a lot of easter eggs in Godzilla: King Of The Monsters referencing to past Godzilla films. If you have not found these references here are the easter eggs that you may have missed.
1. The Maser Cannons
The maser cannons were first introduced in War Of The Gargantuas as "Type 66 Maser Beam Tanks." These tanks would have a tractor tow the main cannon behind them and the cannons would shoot electricity like a giant taser. They would become a main staple of military artillery in the Godzilla series evolving from being towed by tractors to being full fledge mobile tanks. In Godzilla: King Of The Monsters, there is a scene where Godzilla is circling around and attacking Monarch's base. When O'Shea Jackson Jr.'s character was prepping to defend the base we see a glimpse of what he is controlling and they are called "maser turrets." We don't see them in action, but my guess is that they would be like the tasers that we see with Mothra's handlers at the beginning of the movie. It would only be used to stun and not kill the monster.
2. Monarch Outposts
On the Monarch Sciences website, there are containment facility outposts that are numbered. These outposts are outpost 32, 54, 56, and 61. They are all references to a certain date that each monster first made their movie appearance. Outpost 32 is located in Antarctica where Ghidorah is frozen in the ice. If you multiply it by two then you would get 64, which is the year that Ghidorah first debuted in Ghidrah The Three Headed Monster. Outpost 32 is also a reference to John Carpenter's The Thing which also takes place in Antarctica where the researchers are stationed at outpost 31. Outpost 54 is Monarch's main base of operations to study Godzilla. This connects to Godzilla's first movie appearance in the 1954 movie, Gojira. Outpost 56 is Rodan's containment facility and is located in Isla de Mara. Outpost 56 references the year Rodan first debuted in the movie, Rodan. Finally, outpost 61 is references the year that Mothra first made her appearance in her movie, Mothra.
3. The Mothra Twins
Through out the Godzilla series, the Mothra twins (formally known as the Shobijin/Cosmos) would play a prominent role to summon Mothra. In Godzilla: King Of The Monsters, actress Ziyi Zhang plays Dr. Chen. She reveals to Mark Russell (played by Kyle Chandler) during the second act of the movie that she has a twin sister and that she and her sister are third generation twins and third generation Monarch employees. She even pulls out photos of her mother and her aunt together on Infant Island, Mothra's original home. This is the reason why we see Ziyi Zhang's character at two different places at the same time.
4. The Oxygen Destroyer & Dr. Serizawa's Sacrifice
The oxygen destroyer was first introduced in the original 1954 movie, Gojira/Godzilla! King Of The Monsters (1956). This device was accidentally created by Dr. Daisuke Serizawa as he was studying micro-oxygen to help benefit mankind. Instead, he created a chemical that eats away everything organic and destroys the oxygen in the water. He didn't want to use the oxygen destroyer out of fear that it would be used as the same type of weapon as the atom bomb. After some convincing hearing about how many lives were taken by Godzilla and the destruction it caused Dr. Serizawa agrees to use the oxygen destroyer only once. To make sure that his invention couldn't be remade he burns his research papers and sacrifices himself when he faced Godzilla.
In Godzilla: King Of The Monsters, the oxygen destroyer was used like any other bomb that had a green hue in the blast. It was used to stop Ghidorah, but didn't work and instead severely weakened Godzilla. Everyone thought Godzilla was dead until Mothra comes and reveals to them that Godzilla is still alive. They discover not only the hollow Earth theory to be true, but discovered where Godzilla has been hiding in the past five years. Everyone knows Godzilla needs a speed boost on healing his wounds and decided using a small nuclear warhead. Dr. Ishiro Serizawa (played by Ken Watanabe) volunteers himself to deliver and detonate the warhead to Godzilla. Before Dr. Serizawa died, he walks up to Godzilla and says his good-bye to him. The plan works as Godzilla is now supercharged, yet it causes Godzilla's body to become unstable.
5. Mothra's Sacrifice
After Mothra defeated Rodan, she and Godzilla find themselves in an exhausted state. In order to help an almost defeated Godzilla get back up on his feet, Mothra sacrifices herself by being blasted by Ghidorah's gravity beams head on and her energy was absorbed into Godzilla. This scenario was played out in the movie, Godzilla vs MechaGodzilla II. In the movie, Fire Rodan lays on top of almost dead Godzilla and gives his energy to Godzilla.
6. Burning Godzilla
After Godzilla was supercharged again, Godzilla glows bright red, melting everything that touches. Godzilla became "Fire" Godzilla. He gives a bellowing roar at the three headed menace and releases an atomic pulse towards Ghidorah, which burns off the wings and two of the heads. Godzilla gives one final stomp on Ghidorah's chest before Ghidorah and Godzilla explode. Ever since "Fire" Godzilla's reveal, it was no doubt a homage to Burning Godzilla from Godzilla vs Destroyah. This 1995 movie was Godzilla's one last hurrah to end the Heisei series before his retirement. Godzilla vs Destroyah is considered one of the saddest Godzilla films since Godzilla dies from a meltdown. In similar fashion, Godzilla absorbed too much radiation and his body became unstable. After witnessing Destroyah kill his son, he releases a wave of atomic pulses towards Destroyah. Despite releasing so much nuclear energy, Godzilla was still on course for a meltdown and G-Force does everything in their power to reduce the meltdown to a minimum.
7. The G - Team
Ever since the Heisei series, there has always been some form of military team that would act as a defense force to fight off Godzilla and any other monsters that appear as a threat. The first known team was called G - Force and they first appeared in Godzilla vs MechaGodzilla II. Then, G-Force return in Godzilla vs SpaceGodzilla and Godzilla vs Destroyah. After the Heisei series, they return in the Millenium series as the G - Graspers in Godzilla vs Megaguirus, the Kiryu squad in Godzilla Against MechaGodzilla and Godzilla: Tokyo S.O.S., and the M - Organization in Godzilla: Final Wars. Now, the Godzilla defense forces are back as the G - Team and just like G - Force, they fight off any monster threat and were also seen helping evacuate the citizens that live on Isla de Mara before Rodan broke free from his containment.
8. Steve Martin
Before the actor, Steve Martin, rose to fame in Hollywood there was a character in the original American 1956 version, Godzilla! King Of The Monsters, that went by the same name. This character was played by Raymond Burr and his character's role was that he was an American newspaper reporter that witnessed and recorded every detail on Godzilla's attack on Tokyo. Then, Raymond Burr returns in Godzilla 1985 to reprise the role, but his name was changed to Mr. Martin to not confuse the character with the actor. In the ending credits for Godzilla: King Of The Monsters, we see newspaper clippings flashing by telling what happened in the aftermath of the movie. In one newspaper clipping, there was an article about an egg that was found that is suspected to be Mothra's egg. The author of the article was Steven Martin.
9. Kong
Okay, so this is really not an easter egg. This is more of elbowing the idea that Godzilla vs Kong is happening soon. Kong and Skull Island has been mentioned so many times through out the movie that it's sort of hard to miss. He is mentioned at the Senate hearing when Ken Watanabe, Sally Hawkins, and Thomas Middleditch are at a hearing to explain what Monarch does, why the world needs Monarch, and why Godzilla is so important. Kong's name was seen when Kyle Chandler was scrolling through the list of monster voices the Orca can imitate. Skull Island was mentioned again as one of the locations where the monsters are acting sporadic after Ghidorah wakes them all up. Even in the end credits, there are articles talking about all of the monsters that were unleashed were heading to Skull Island and the monsters over there are starting to acting up. Another article mentions about the monsters having a long history of grudge matches and if humanity will be caught in the cross fire. Another article talked about Skull Island becoming unstable. Then finally, the end credits reveals a cave painting of Kong and Godzilla fighting.
10. MechaGodzilla/Mecha-King Ghidorah
The last easter egg that can be found, but is really hard to miss if you are not looking hard enough. It is at the end credits once again in one of the newspaper clippings. It reads, "De La Rosa went on to claim that Monarch was not only developing this mechanized giant on Skull Island, but had already tried to create organic Titans in the past and that they are the cause of several of the recent Titan incidents." MechaGodzilla first appeared in the 1974 movie, Godzilla vs MechaGodzilla, and became a reoccuring opponent through out the series. Mecha-King Ghidorah first appeared in the 1991 movie, Godzilla vs King Ghidorah, and only made one movie's appearance. It is unknown if this is hinting towards MechaGodzilla or Mecha-King Ghidorah, but many are convinced that based on the post credit scene when Alan Jonah (played by Charles Dance) buys Ghidorah's head he is going to turn it into Mecha-King Ghidorah. To me, I don't think he will go that route since part of what his character does is pirate DNA of the monsters. I think he is taking Ghidorah's head and extract Ghidorah's DNA to splice up his own monster. MechaGodzilla can be what the article is referring to. That's just me though.
Those are all the easter eggs in the movie that I can find. Let me know if you have found any that I missed or your thoughts on what this mechanized giant could be in the comments section. Also, make sure to follow me on my Facebook and Twitter pages to stay up to date on more news, reviews, and discussions.