Avengers: Endgame was originally going to be the end of the Marvel Cinematic Universe's Phase 3. However, Marvel Studios boss Kevin Feige recently confirmed Spider-Man: Far from Home will actually close out Phase 3 and lead us into Phase 4. With that being said, it looks like Endgame may have left us with a pretty big plot twist for Far From Home and the future of the MCU. There are MAJOR Spoilers for Avengers: Endgame below, so read ahead at your own risk.
One of the final scenes from Avengers: Endgame has Peter Parker back from the dustbin and greeting his best friend Ned Leeds at school. The Russo Brothers have revealed Ned was Decimated at the end of Infinity War too, which explains why they're both still in high school five years later. The obvious focus of this scene is the heartwarming reunion between Ned and Peter, but some eagle-eyed MCU fans may have found a pretty huge Easter Egg lurking in the background from another recent Marvel project.
If one looks really closely, there is an administrator greeting students and giving high fives. Could this be Ben Mendelsohn's Talos from Captain Marvel? A certain group of MCU fans believe that it is and this could have some pretty huge implications for Spider-Man: Far From Home and the MCU's Phase 4. While Talos begins as a villain in the Carol Danvers standalone movie, he later becomes an ally. Could he end up going back to the dark side in the decades since Captain Marvel took place? It is entirely possible that he could, which might mean Marvel Studios is setting up the Secret Invasion for Phase 4.
The Skrulls might be on the hunt to take over Earth at a certain point in the MCU's future. This has been talked about ever since it was revealed Captain Marvel was coming to the MCU. With that being said, there would still have to be a lot of groundwork put down before this could even become a reality. Mainly, we'll probably end up seeing a lot of Skrull action in Spider-Man: Far From Home in terms of taking on human appearances if this theory proves to be true. Maybe Mysterio won't be the only main antagonist with the Elementals after all.
Obviously, this theory is all based on an image and shaky video from a movie that is still in theaters, meaning it's not the highest quality source. It's a picture and video taken from an Avengers: Endgame screening and it's hard to make out who the character is in the background. But, it's not a stretch to think of Ben Mendelsohn having a small cameo in the movie since just about everybody to ever appear in the MCU is in the movie. Is Marvel Studios really teasing a Secret Invasion movie for Phase 4? Or could Talos be an ally? Or is this just a blurry picture of Bigfoot? Hopefully we'll receive confirmation in the near future. This MCU Phase 4 theory originated from Reddit.