This honestly reads like you don't watch a lot of movies, which is fine! The audio was really bad, which makes it nearly impossible to follow without subtitles. But with subtitles, this film is very middle of the road in terms of timeline ambiguity. I also don't think an ambiguous timeline is bad, if it recontextualizes a scene.
I mean in that Einstein scene, they are cutting footage of RDJ telling Oppenheimer he's a patriot who ran the Manhattan project with footage of him as a bumbling student people made fun of. That was definitely not a "big plot twist," they are explicitly saying it was after the war, even if it was momentarily confusing because so much is going on. I thought it was a pretty rewarding film to pay attention to.