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.
Factual error: The idea that humans only use 10% of their brain is a widely-circulated myth that has been debunked by neurological science many times over.
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.
Revealing mistake: When Lucy is chained and locked up in the room by the Korean drug cartel, she is hit in the stomach by the Korean guy. Drugs start leaking into her stomach and her body, and she starts shaking and going up the wall and ceiling. When she is leaning against the wall and crawling up it, the way the gravity affects the chains and her hair shows that she is actually lying on the floor. (00:25:20)
Factual error: When Lucy is on the chair traveling through time, she's in Manhattan and goes back to the time before Europeans, where there are plains Native Americans on horses. Wrong Native Americans, and they didn't have horses yet.
Visible crew/equipment: When Jii and his men are preparing to attack Lucy after she meets Professor Norman in person, the shadow of the camera can be seen on the backs of Jii's henchmen as they take their weapons out of their cars.
Other mistake: In the hospital scene wherein Lucy disarms the gunmen and retrieves the briefcase of drugs, she plunges her hands inside a fallen man's abdomen to retrieve the last bag of drugs. Her hands are thus drenched in fresh, bright red blood. Lucy immediately steps to the corridor doors, places her bloody right hand against the door (plainly touching the glass) and pushes it open. But when she pauses and turns away, there are no bloody handprints, fingerprints or blood smears anywhere on the door.
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.
Revealing mistake: After the drug addict gets shot, one of the henchmen lifts the dead drug addict's leg up and the other leg lifts up with it before the second henchman had a chance to grab it. It looks unrealistic as if it is a prop rather than a real human being dragged.
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.
Factual error: At the start of the film, cells are shown dividing. As each cell divides, the two new cells separate from each other and move apart from one another. In reality, cells do not move apart after dividing, but remain attached to one another.
Factual error: When Lucy is in the Chair, traveling back in time to meet the original Lucy, she finds herself still in the New York geographical area. However, the original Lucy would have been in Africa, specifically Hadar, Ethiopia. After Lucy touches her finger, she flashes once again, transitioning from the former New York City area to the vast universe.
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.
Revealing mistake: In the scene where Lucy causes the bullets to fall out of a loaded pistol the casings that hit the floor have a firing pin mark in the primer with the bullet in the casing.
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.
Visible crew/equipment: When Lucy is calling professor Norman, the crew and light are visible in the bell jar. (00:43:20)
