Luke was going to embrace the Dark Side

Return of the Jedi’s ending is the very definition of satisfying. The heroes emerge victorious, the Empire is beaten and Darth Vader is redeemed and returns as a Force Ghost in his original form as Anakin Skywalker.

However, the movie almost ended on much darker note.

After Vader saved his son Luke Skywalker from being destroyed by the Emperor, the Jedi Knight would have taken his badly-injured father to a nearby ship, only for him to pass away from his injuries.

George Lucas then suggested that Luke should “take his mask off. The mask is the very last thing—and then Luke puts it on and says, 'Now I am Vader".

However, the idea of the hero suddenly embracing the Dark Side in the closing scenes didn’t sit well with the visionary and instead the end focused on Vader's redemption and reconciliation with Luke and freedom being returned to the galaxy.