My head cannon is that ESB is accidentally more accurate than the rest of Star Wars, Nolan’s Interstellar-style. Time might pass differently on the surface of different planets versus space?
You’re exactly right. I would go as far to say that it isn’t even accidental.
I wouldn’t go with an Interstellar explanation with it. Maybe Dagobah has a weird relationship to the Force that drives the flow of time in a different manner than the rest of the universe?
Invoking Interstellar implies to me that it was Luke’s training which was dilated in time since the time dilation of Interstellar happened mostly on the water planet, but in this case it would be as Duracell said and be the dilation of time on the Falcon as it traveled at near-light speed. For a normal observer such as Luke or Vader, the events of the film would take place over many weeks while Han and Leia would experience only a few days.