When Cap hides in Peggy Carter's office at Camp Lehigh in the past Peggy is apparently going over some situation with underlings that includes some agent named Bradock. She says something about how the lightning being investigated isn't natural lightning and that someone called Bradock hasn't checked in as he was supposed to.
Many are jumping to the conclusion that this is about Capt. Britain. Thing is... Joe Russo on a podcast was far from confirming that take on the dialog and said this:
“I think we uh, maybe… or maybe it’s just a guy named Braddock [laughs].”
So, I would right now put this in the same category of those thinking that the Roberto Da Costa name in the memorial Scott Lang goes to in San Francisco as being a reference to the New Mutants character, which is to say... fans reading too deeply into something seeing what they want to see.