In issue 6, the Sentress reveals she's been depowered, with no knowledge of when her powers may return. The letters' page also promises that she'll continue to hold the same Good Old Ways values people love about her when she returns to action (Carol Danvers as Ms. Marvel was created to be a feminist icon).
The letters' pages are chock-full of this. One of them says that the Sentry may one day join the ranks of the Mighty Avengers, or "some other new Avengers group", and another has the reader asking if the book will tie in with Marvel Zombies, to the editor's confusion.
Lampshaded by an author's note in The Avengers #71, where a time-displaced Cap from the past wishes he had a disk-shaped shield that could be thrown.
In Issue #6, Christian is is shown watching a news cast about the Original Five X-Men in his room.
In Issue #16, Emma and Astrid are at the library and Emma finds herself bombarded by the thoughts of everyone else. Astrid tells her to visualize something strong to help her block out the thoughts. Emma visualizes a diamond, referencing her gaining the ability to become diamond in Grant Morrison's X-Men run.
Fury: My War Gone By: In The Punisher, Barracuda is missing a significant amount of his teeth, and has replaced his missing front teeth with a grill that reads, "Fuck You." If one looks closely as Nick Fury beats Barracuda to near death with a club the teeth that are replaced by the grill are the exact same ones that got knocked out.
A storyline in the late 70s employed Moses Magnum, a villain who had previously fought Power Man and had now gained superpowers in what was more or less an accident. The extended reprint in Classic X-Meninstead depicted him as having been rescued and empowered by a guy calling himself Apocalypse, who wanted him to cause chaos.
In X-Men: The Hidden Years, Mastermind fails to trick Jean Grey by making the Blob look like Cyclops. He concludes that he'd need to come up with a more detailed illusion over a period of time.
In the X Men First Class oneshot Iceman & Angel, Bobby discusses how totally cool it would be if Warren's wings were made of knives.
X-Men (2019): Moira's Journal has several instances of this:
In one entry, she worries that by breaking Xavier, she will "fracture his psyche and eventually unleash something unexpected on the world," which is a Call-Forward to Onslaught.
In another entry, she states that Xavier had an idea that will eventually become the Five working as a resurrection machine — but that they need a mutant that can manipulate reality. Moira then states "I have used my expertise in genetic modification to find potential matches for both Charles and me to produce a mutant," meaning that she probably set him up with Gabrielle Haller to produce Legion and set herself up with Joseph MacTaggert in order to produce Proteus.
