Wyatt Russell revealed that he originally auditioned for the role of Captain America for Captain America: The First Avenger (2011) and that it was his very first audition. Chris Evans got the role and Russell got to play the next incarnation of Captain America in this show.
The Smithsonian Museum Captain America tribute first seen in Captain America: The Winter Soldier (2014) is seen throughout the series. Many of the displays featured in it come from the MCU Captain America films including one of the posters being the 1st issue of Captain America comic book, the newspaper article of Captain America saving the child, the uniform of the Howling Commando named Pinkerton, weapons the Howling Commandos used in World War II, a newspaper article of the Howling Commandos destroying HYDRA factories, Steve Roger's 4F rejection form, Cap's poster as a war bond salesman, and Cap's bike and original shield from Captain America: The First Avenger (2011) as well as the uniform Captain America wore in The Avengers (2012). The Bucky section is expanded to include his time as the Winter Soldier and the Sokovia Accords.
For the first time in the MCU, Baron Zemo makes an appearance in full costume with the character's famous purple mask. His costume is modeled after the character's modern costume with a black trench coat. However, the trench coat in this series has white fur with black polka dots on the collar, which was featured on the shoulders of Zemo's original comic costume.
Florence Pugh and Chris Evans had filmed cameos for the series as Yelena Belova and Steve Rogers respectively, but they were both cut from the final product. Yelena's appearance was removed due to the delay of Black Widow (2021), though why Steve was taken out is unknown.
Karli Morgenthau, played by Erin Kellyman, is a female version of the character Karl Morgenthau, the Flag-Smasher, a supervillain fanatic dedicated to establishing a one-world government by violently attacking the symbols of nationalism, who first appeared in "Captain America" (Vol. 1) issue #312. In the comics, he leads an anti-nationalist terrorist organization called The Underground Liberated Totally Integrated Mobile Army To Unite Mankind (ULTIMATUM).