At the end of the training remote session with Luke talking to Ben, what are the green ovals in the top right with white scribbled lines for?, in the last sentance or so before you cut to the Death Star board room
I think those are just reel change markers. It’s something we no longer see in digital projection, or on home video, but would definitely be present in 1977. See https://en.wikipedia.org/wiki/Cue_mark for more info.
Hope that helps. 😃
Or you can watch this scene from TV’s “Columbo” …
https://www.youtube.com/watch?v=X_ol8PbN_94(at 50:01)
…when the detective gets a crash course in reel changes. This is where I learned what that bright colored oval flashes were. 😃