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.
Continuity mistake: During the missile barrage on the dark planet, one of the soldiers says, "The planet has increased in diameter by 200%." That means that the diameter would be triple the original size, but it's obvious from the missile impact animations that it hasn't grown anywhere near that much.
Continuity mistake: When David is waiting for the priest and Leeloo before attempting to board the shuttle to Phloston Paradise, he is chewing on the nail of his index finger. The shot changes to show a different angle of him and he is now chewing on his thumbnail with no time for him to have changed position.
Continuity mistake: When Zorg is showing the the guns to the Mangalores, he is seen shooting the Police dummy, and when he turns to show them that every shot fired afterwards goes to the same place, he is seen starting to fire from his right to the left, but when the camera angle changes he is seen starting from the right again.
Revealing mistake: Whilst Diva Plavalaguna is singing, you can see the back of her head creasing and bending. This is because the suit that the actress is wearing is made out of foam latex; confirmed by Nick Dudman, Creature Design Supervisor on the DVD featurette "An Audience With Diva Plavalaguna".
Revealing mistake: After Korban meets Ruby and everyone leaves them alone, Korban grabs Ruby by the neck and holds him to where his feet can't even reach the ground. In the first shot, you can tell that Korban's hand isn't even applying pressure. In the next few shots of Ruby, still being held off the ground, you can now see that Korban's applying a little pressure now, but probably not as much as there should be while holding a full grown man a foot off the ground.
Continuity mistake: When Corben bails on the 5-0 (in his taxi with Leeloo), he yanks the police car's winch right out of the car (which resulted in dragging the winch, as well as the entire length of the cable behind his taxi). In the next shot showing his car (4 police cars chasing him down the "street"), the cable and winch have disappeared.