In a recent interview with director Joss Whedon, he sends fans guessing and looking forward more to the date of release. Marvel Entertainment's Lorraine Cink asked Whedon: "Will we be seeing Marvel characters who aren't yet in the preview photos? Are we going to be seeing other Marvel characters that we've seen in other films or other parts of the universe?" To these pivotal questions, he answered a definitive "Yes."

Since then, theories have already circulated as to who these characters could be. The popular guesses include Thanos whom the first movie alluded to. Black Panther is also a candidate. Although his appearance has been slated for another Marvel film, Civil War, fans can't help but hope that he will make an appearance. To them, this would lay groundwork for the upcoming film. The third character that the audience think could make an appearance is the Red Skull. He played such an important villanious role in Captain America's life that fans feel it would be strange to just have him around for such a short time.

Rumors and suspicions will seem to increase as May 1 grows nearer. Whoever the other "secret" characters will be, the audience can still look forward to the returning cast which consists of Robert Downey Jr. who plays Iron Man, Chris Hemsworth as Thor, Mark Ruffalo as Hulk, Chris Evans as Captain America, Scarlett Johansson as Black Widow and Jeremy Renner as Hawkeye. The new trailer shows that additional characters will also come into the scene: Pietro Maximoff also known as Quicksilver (played by Aaron Taylor-Johnson) and Wanda Maximoff who is popularly known as Scarlet Witch (played by Elizabeth Olsen).The main villain for the film is James Spader also known as Ultron - a technological figure that wants to see the extinction of the human race.