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.
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.
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.