Star Wars Episode 1: The Phantom Menace - Automatic Lightsaber
In the part when Obi-Wan rises up from the pit & rises up to strike Darth Maul,you know how he uses the force to reach up & get Qui-Gon's lightsaber,he doesn't turn it on.He never touches the button!
actually this is NOT a slip up
in the star trek universe it has been stated numerous tiems that only a jedi can turn on a light saber (there actually is no working button onthier exterior) . the only really HUGE slip up in this regard is in episode 5 when han solo turns one on to cut up his snow beast so he can stick luke in it to keep luke from freezing to death