Of course, it wouldn't be a Marvel movie without a surprise cameo, and Captain America: Brave New World has a major one. It reunites two The Falcon and the Winter Soldier stars.
Warning: Spoilers ahead for Captain America: Brave New World
While stopping a conflict between the United States and Japan at Celestial Island, Sam Wilson/Captain America (Anthony Mackie) watches his protege, Joaquin Torres/Falcon (Danny Ramirez), get shot out of the air. He lands in the Indian Ocean, and luckily, a search team finds him.
Still, Torres needs surgery. He is transported back to Washington, D.C., for his operation. Wilson watches as the surgeons do their work on him.
That is when Bucky Barnes (Sebastian Stan), better known as the Winter Soldier, appears. He is there to comfort his friend, who is clearly distraught.

Wilson is starting to doubt himself as Captain America — after all, he did not take the super serum. However, Barnes promises that Steve Rogers (Chris Evans) did not make a mistake with his choice.
Barnes then gives a long-winded triumphant speech, which Wilson calls him out for, asking if his speech writers helped him with it. Of course, they have had a rocky history, but they are good friends now. “I love you, buddy,” Barnes says to Wilson before leaving.
The talk helps Wilson ahead of his confrontation with Samuel Sterns (Tim Blake Nelson) and, later, Thaddeus “Thunderbolt” Ross (Harrison Ford) after he transforms into the Red Hulk.
Why the Captain America: Brave New World cameo matters
Marvel fans know that Bucky Barnes and Sam Wilson go way back beyond Captain America: Brave New World — they recently appeared in The Falcon and the Winter Soldier together.
They first met in The Winter Soldier before sharing more screen time in Civil War. They initially hate each other, but they slowly begin coming around to each other in the subsequent years.
In The Falcon and the Winter Soldier, they work together as Wilson attempts to regain the Captain America shield. He eventually earns the mantle back by the end of it.
Barnes is now a politician, setting him on a very different path. Still, he seems ready to dive back into action whenever needed. Expect them to reunite again when Avengers: Doomsday and Secret Wars come around.
Plus, Barnes will soon be seen in Thunderbolts* as well. He is one of the antiheroes featured on the team. Stan will star in it alongside Florence Pugh, David Harbour, Wyatt Russell, Lewis Pullman, Olga Kurylenko, and Julia Louis-Dreyfus.
There is another cameo in the movie as well. However, it was revealed before the movie's release, so I am not sure it is a “surprise” to anyone.
Liv Tyler returns as Betty Ross after playing the part in The Incredible Hulk. Ross talks about his fractured relationship with Betty, and her first appearance comes when she answers a phone call from her dad. Later in the movie, she shows up on-screen to visit him while he is imprisoned on the Raft.