1. The Collector's Museum - Guardians of The Galaxy
The Collector's museum is first shown in the Thor: The Dark World mid-credits sequence. We have a much more comprehensive look at his collection when Guardians is released. Adam Warlock's cocoon, which can be seen in both movies, is the largest egg concealed here.
An orange icon-filled holographic map of the globe is present as Tony and Nick Fury are meeting at SHIELD. Over Nevada, where we know Thor's hammer resides, there is one circle. Comic book fans will recognise one as the MCU's homage to Namor, the undersea hero, and the other as one over the middle of the Atlantic Ocean proclaiming the existence of Black Panther and Wakanda.
There are a variety of technology on show as Steve and Bucky are investigating the Stark Expo at the start of The First Avenger. You see an example of a man who can transform himself into fire from the front and rear. Due to restrictions at the time, it doesn't explicitly state that it is the first human torch.
A scene with a fictitious Pietro, Wanda, and the twins discussing trick-or-treating may be seen in Marvel's WanadaVision. "Kick-ass," one of the lads replies. As a result, a reference to the Evans Peter and Aaron Taylor-Johnson film Kick-ass is made.
When they bring up Stephen Strange, Captain America and Falcon are questioning Jasper Sitwel in Captain America: The Winter Soldier. This statement is our first mention of the sorcerer Doctor Strange, even though the Marvel film Doctor Strange won't be out for another two years.
Mjolnir, the hammer of Thor, is shown touching down on Earth in the Iron Man 2 post-credit sequences. Thor was the second MCU film to hit theatres. Marvel is teasing upcoming movies and interesting tales as more information like this comes to light.
We catch a peek of the fabled infinity gauntlet in Thor's arsenal vault. As a result, fans started to become eager to see Thanos enter the MCU.
In Spiderman Homecoming, Bruce Banner is mentioned. There is a list of the greatest scientists in history in Peter's class. The Incredible Hulk, commonly known as Bruce Banner, is included on this list.
Loki. Loki is the answer. The guy who hijacked a jet in 1971 between Portland and Seattle, Washington, went by the name D.B. Cooper. Loki may be seen seated in a passenger seat during a scene cut to the interior of a 1970s flight in Loki episode 1. When Loki delivers a flight attendant a message, she addresses him as "Mr. Cooper."
The cover of The Avengers comic issue 223 has a sinister image of Hawkeye poised to fire an arrow with Ant-Man perched on top of it. As a result, it appears on the big screen in Captain America: Civil War from 2016.