At the start of Doctor Strange (2016), the Ancient One is wearing her hood while she bends matter freely to stop Kaecilius. This is to cover her forehead to hide the fact that she is channeling power from the Dark Dimension (which is revealed later), which is why Kaecilius calls her a hypocrite.
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.
In Avengers: Infinity War, Mantis sets her hands like an actual praying mantis when sneaking on Thanos.
In Captain Marvel (2019), when Monica is changing the color of Carol's suit she first chooses a combination of red and gold, the same colors of DC's Shazam, who was previously known as Captain Marvel.
Black Widow casually saves both Falcon's and Captain America's lives in Captain America: The Winter Soldier. When Bucky is shooting at these 3, he targets black widow first. She dives forward. She then pushes cap and Sam's heads out of the line of fire (watch the head cushions explode).
After stabbing Thanos, Gamora's sword doesn't have any blood stain or blood drops on it indicating its a fake reality.
In Thor: Ragnarok, the carcass that Valkyrie lands on is a bilgesnipe, a creature described by Thor in The Avengers.
In The Avengers (2012) Pepper Potts is barefoot in stark tower whilst Tony Stark wears shoes. This was done to mitigate the height difference between Gwyneth Paltrow and Robert Downey Jr.
In Black Panther, Shuri asks which side of the road should she drive on due to her education in England as England drive left and most of the countries drive right.
Thor Ragnarök: Hela's bruises disappear once she reaches Asgard, along with the cracks on her skin. Previously it is mentioned that her power increases when she's on Asgard.