10 More Star Wars Mistakes You Can't Unsee
4. Vader Randomly Carries Two Lightsabers - Episode VI: Return Of The Jedi
Not long after Darth Vader hurls his unmistakable red lightsaber at his baby boy - with that blade weirdly firing out of the wrong end for a moment - the fallen Jedi learns of the existence of his own daughter after Luke's thoughts betray him in The Emperor's Throne Room.
However, there was actually another shocking development in this dimly lit battle between father and son that most folks didn't catch as Vader contemplated turning Leia to the dark side.
Focus on Vader's left hand whilst he wanders around in the darkness after noting how Obi-Wan's failure was now "complete" and you'll never be able to unsee what seems to be another not yet ignited lightsaber.
This was actually left behind from a deleted moment (via The FIlm Theorists) during their duel when Vader would have somehow got ahold of Luke's lightsaber and duel wielded them against his own flesh and blood.
Director Richard Marquand clearly still loved this particular shot of the masked icon ominously hunting down Luke on the second Death Star, though. So, this easy to miss double-bladed continuity error ultimately survived the editing process, with Skywalker strangely holding that same lightsaber in the very next shot.