Captain America: The Winter Soldier who played Peggy Carter in "Captain America: The First Avenger", said that she would not appear in the sequel. However Stanley Tucci, who played Dr. Abraham Erskine in the previous film, later said that Atwell would reappear in a flashback scene. Also in January, Marvel Studios announced that the film would be released in 3D, and Anthony Mackie said filming would begin on April 1, 2013. Later that month, Toby Jones, who portrayed Arnim Zola in the first film, said that he would reprise the role in the sequel. By the end of the month, stages were being built for
Captain America: The First Avenger team of that name, and in November Johnston refuted speculation that the Sub-Mariner, an Invaders team-member in the comics, would be included. Johnston later explained that "the Invaders" had been discussed simply as a possible name for the squad of commandos Captain America leads in the film. Christopher Markus, one of the screenwriters, said the unnamed group was "called the Howling Commandos in the script, but no one says that out loud." The design as a whole tried to create technology that could be built in the 1940s, though with the added Cube technology in Hydra's case. Abandoned Nazi projects