In Deadpool 2, one of the rednecks talking about toilet paper is actually Matt Damon in four hours worth of prosthetic makeup.
In
Guardians of the Galaxy, when Peter Quill is arrested, it shows that he
has a translator in his neck, which is how he’s able to speak to
different alien species.
In
Spider-Man: Homecoming Bruce Banner’s face is alongside the other
“famous scientists” on the wall of Peter Parker’s physics class.
In Spider-Man: Homecoming, Michelle (MJ) is reading a book titled “Of Human Bondage”, a story of an orphan boy sent to live with his aunt and uncle.
Thor (2011). Thor calls Coulson “Son of Coul” in the same way he is called Odinson.
In Spider-Man: Homecoming, the url of the video that Peter watches on youtube is the exact same as the url of the second Spider-man: Homecoming trailer other than"P" being switched for “p”.
In Captain America First Avenger (2011) Johann Schmidt gets blood on his uniform staining the skull red foreshadowing his eventual turn into Red Skull.
In Iron Man 3, Tony Stark has a statue in his house containing pieces of the Formula 1 cars that were destroyed in Iron Man 2.
In Avengers: Age of Ultron and part of Ragnarok, Thor has a strain of Loki’s hair braided into his own.
In Captain America: The First Avenger you can see on Steve’s enlistment forms that he is born on the Fourth of July.
In Iron Man 2, whilst Tony is looking through his father’s notes a two page spread can be seen dedicated to the mathematical concept of a Tesseract. Two films later a cube called the Tesseract is introduced which goes on to play a major role in several MCU films.
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