Continuity mistake: By the end of the movie, when Lucy is sitting in the chair and her skin turns black, we can see her arms slowly turning black as well. When camera cuts away and shows Lucy from behind, her arms are naturally white again.
Continuity mistake: As Lucy begins to change into a black mass, you can see that mass destroying the wood floor. But, in the final shot, as you are looking down on the dead triad boss, the floor is perfect, with wood scraps scattered on it.
Continuity mistake: When Lucy breaks free from the cartel prison room and kills the fellow members we see her eating then removing a bullet she grabs a bag that is half full and begins to add more weapons and items when she lifts the bag from the table for the final time there is less than half a bag.
Continuity mistake: After her friend Richard coerces her to go into the hotel with the case to meet Mr. Jang, the man behind the counter who is talking to Mr. Jang asks her name. She says Richard is parking the car and he shows up at the window outside the hotel. Before he is shot, there is red 'blood' already on the window that was not entirely wiped off from previous takes.
Continuity mistake: A German drug mule is shot by a Taiwanese drug dealer. By the way his head moves backward, you would think he was shot in the head. When he falls, we see no bullet wound anywhere.
Continuity mistake: When Lucy is in the chair in the room with the scientists, the mob guy launch a shoulder fired missile into the room, and then the room explode, both Lucy and the scientists are hit, and then Lucy goes back in time. After that when it goes back to the room when the mob boss is about to shoot Lucy's head, the room, Lucy and the scientists are unimpaired.