Other mistake: In the scene in the beginning when you first see the fifth element, and the camera moves up so you see the wide open mouth, look to the shoulder on the left. In the years of undisturbed dust, there are a few finger prints. (00:09:35)
Other mistake: When the two police officers are searching for Korben's taxi, as one police officer asks "How do they expect us to find anything in this... ", both police officers have the same ID number on their helmets. (00:39:15)
Other mistake: When Leeloo escapes onto the ledge and goes around the corner of the building, there are people walking across a small bridge. One of these people vanishes in the middle of the bridge when walking to the left. (00:31:20)
Other mistake: Leeloo jumps from the ledge and falls straight through the roof of Korben's cab like it was made of paper. But a few seconds later, the police open fire on the cab and the bullets don't penetrate.
Answer: I looked it up and it is Jill Milan. If you do a search for her, it is in her credits as an actress.