Revealing mistake: Right after they "create" Leeloo and she is lying in the plastic cage with the little straps on her, the guy approaches her and says, "if you want out, you are going to have to work on your communication skills." She gives him a dirty look, and then you can see a huge hole, pre-cut in the glass, that she busts her hand through.
Continuity mistake: When Billy shouts at the Priest while holding the gun, there is a tripod standing behind Billy to his right. Billy yells, "Don't move." The shot changes to the Priest and then back to Billy again when Billy says, "I have a gun" you notice that the tripod behind him has disappeared. The tripod reappears in the overhead shot where the Priest says, "I'll explain everything."
Continuity mistake: When Leeloo is learning English using the Priest's computer, just before David asks him what she's doing, Leeloo is looking at words beginning with "na" (such as "nasty") but as soon as the shot changes she is looking at words beginning with "matt" (such as mattress). Just before she selects "martial arts", she is looking at the following words : master, mastered, mastering and meadow. Firstly, "master" (et al.) all come before mattress in the alphabet, and secondly, mattress (and lots of other words) are between mastering and meadow.
Continuity mistake: The very first scene of the movie the boy rides in on the donkey and has a stick in his right hand he uses to hit the left side of the donkey. The shot changes and another boy yells, "gaka lama lako." and the shot changes to where the camels grunt, notice that the camels, from right to left are as follows in color: beige, beige, white, beige. The shot changes to boys shouting, then the shot changes to the boy about to get off the donkey, but notice the stick in that boy's hand has mysteriously disappeared. The boy gets off the donkey and runs up the platform, and this is where you notice the order of the camels has changed to: beige, beige, beige, white.
Continuity mistake: When the cops go looking for Korben and Leeloo in the fog, there are two orange light sticks hanging from the ceiling inside their car. From the outside looking in they are swinging from side to side very quickly. But from the inside looking out they are swinging from side to side very slowly.
Continuity mistake: When the techs are analyzing the dark planet right before the first attack, the first tech turns to the second to report the sudden drop in surface activity. Between that shot and the following one on the second tech, the first tech's hand jumps from at his side to rising in front of his chin.