I include a lot of easter eggs and cameos in my comics. Usually they tend to be obscure British children's characters from TV series that nobody watches anymore or literary characters. In a crowd scene I included once, in order: Baron Greenback, Bungo Womble, Feathers McGraw, Huxley Pig, Dill the Dog from The Herbs, Kaa (Kipling's Kaa, not the Kaa from that DAMNABLE film), a Flump, and a Clanger.
In chapter seven, I included Ernest the Policeman, PC Plod, Larry the Lamb, and Mr Growser.
I always have a lot of fun with these! For my latest project I did this panel:
The old version of my current work in progress had this poster in the corner of a panel:
As well as this headline on a paper:
Also this guy on one of the advertisements:
Yeah I love Easter eggs lol
My manga has ones related to mythology and the occult. I wont say what they are to ruin them.
But, Ive gotten only 2 comments from 2 different people being aware of what they are so far.
Well, way back in chapter 1, I added in this meme when it was relevant
Emerald has a poster of Super Saiyan 2 gohan in her living room
The guy that Isham was caught draining the blood of falls in the Peter Griffin pose
Not really much of an Easter egg, I just wanted to plan out that Emerald's mailboxe is shaped like a pelican
Just outside of the restaurant that Isham and Emerald have their dinner at during their first date is the temple of heat, and on it has the first depiction of any of the gods in the story in statue form.
A recreation of American Gothic
This guy in the crowd at the stunt show is wearing a sonic adventure two T-shirt
This proposal is actually between two characters in the background that will be significant way, way later.
also right next to them is someone wearing an imagination Institute (from journey into imagination with figment from Epcot) T-shirt 
The pineapple on the hilt of Esen-Ali's sword is the first hint that she is an angel (this is a joke on how apples are the fruit that represent demons, so Argo, pineapples must represent angels)
Humanized versions of tangle the lemur and whisper the wolf in this flashback crowd scene
Again, this isn't much of an Easter egg, I just want to point out some of the things that are happening in the Crossview section of the hospital scene that a lot of people might miss
A herd of wild imps is seen to foreshadow Kno's pet imp
Emerald has a Pikmin shirt as she is leaving the hospital
Sisyphus in Hell
The background behind Lolly here is a rather infamous piece of modern art known as
Who's Afraid of Red, Yellow and Blue
I don't know what this is called, but this was seen in one of the adventure Time episodes taking place in the nightosphere, only in adventure time it was kind of like a bus, I made it kind of grosser
If you know anything about Pokémon, you will know why Absol appearing on Emerald's sweater is forboading.
The flying boar appears in between on top of the panel where Isham is talking about avatar the last Airbender, specifically The Swamp
A referee to top pcs from a dead comic I hope to recreate someday. I guess that kind of makes it an Easter egg and foreshadowing at the same time
There are a bunch of easter eggs in this image:
The orange book lying down on the bookshelf on the left is Something Like Summer by Jay Bell. This is another comic on Tapas, as well as being a series of novels.
The plant on that same shelf is Audrey III, a shoutout to Audrey II from Little Shop of Horrors
The two books laying on the sideboard behind Jake (yellow shirt) are Resonance by River Kai (a series on Tapas) and Drive by Dave Kellett
The book on the coffee table is my own Wild Nights, Hot and Crazy Days
In this image most of the background characters are cameos from other creators' series. In a sort of double easter egg, I am also in the crowd (Tall dude with glasses, back row, left side):
IN this image, the horse is @pjthetoonaddict's Otto if he lived in the shapeshifter world (we had discussed this - Otto also appears in human form in the image above, far left). This is also one of the last images that I drew in this style, because drawing "smooth" lines was becoming more and more difficult for me (I have very shaky hands). : 
I do this stuff all the time;
Oh? A movie? (The Lies of a Heartbreaker)
wrong, old comic! (Tales of an Executioner)
Hmmm who's those folks in the background? (The Alp's Assassin)
Oh! just the MCs from the prior comic! (Rune's Grand Adventure!)
What an odd collection of movie icons! (The Angel's Guardian)
Oh it's just the other comic's title page! (Need I say the title? It's right there.)
There's more, of course, but I've name dropped every comic I've done thus far. I really needn't go on.
I'm a child in the body of an adult ^^'
Plus in the second panel, Johan and Xar are Osrams great-great[...]-great-parents 
I actually found an old drawing of them
The amount of funnies, memes, references, and foreshadowing I somehow squeezed into this single panel is straight up outrageous.
Can you find them all?
You don’t even need to have that much meme knowledge. Just zoom in on the labels in the panel, then you’ll find everything. I think there are two references, 2 to 3 memes, 2 cases of foreshadowing, the rest is just silly anatomy stuff.
Edit: I actually forgot that there are 4 memes and 3 cases of foreshadowing lol. This is what happens when you have too much fun with a single panel.
I have a few references to series I enjoy like ATLA or Castlevania, but I also have personal references. Andrew's Knights of the Round Table is a group mentioned in the history of the world, but is a reference to a previous draft of the story. The numbers 38 and 54 come up a lot and those are references to old gametags of mine.
One thing I forgot to mention last time is that the pirate on the pirate R's cereal is modeled after the pirate on the Pirates of the Caribbean ride poster.
in "The Journey" in one of the recent chapters I established that a group of teenagers went missing at a campsite, the names are the names of the teens in "Friday the 13th" original movie
My manga doesn't have much content yet, so there are only these two easter eggs:
1.The hand from the L4D2 (Left 4 Dead 2) game cover
2.The sign on the left reads 'Tabehoudai (食べ放題)', which means 'all-you-can-eat restaurant'. In fact, the term 'Tabehoudai' didn't exist in ancient times - it's a modern word, but who cares XD
Post art/ panels based on festivals/seasons/traditions (real world & fictional)