Star Wars: 20 Things You Didn't Know About The Empire Strikes Back
6. James Earl Jones Thought Darth Vader Was Lying About Luke's Parentage
Though some fans at the time doubted Darth Vader's claim that he was Luke Skywalker's father, this also transpired through to at least one member of the cast, given that Vader's voice himself, James Earl Jones, assumed it was a lie intended to manipulate Luke.
Jones believed this until he finally sat down to read the script for Return of the Jedi a few years later, and given that Jones' voiceover is one of the more compartmentalised aspects of the production, it's entirely possible he wasn't given the script until after principal photography was completed.