Continuity mistake: After Leon rescues Mathilda from the SWAT team and dodges the snipers, he shoots out a ventilation fan to make an escape route. He gets off two shots before we see the vent, but when it does we see about 7 bullet holes around the vent. Then the camera goes back to Leon as he continues firing. When the camera switches back, the holes around the vent are different. (01:27:05)
Continuity mistake: Before the dreadlocked man starts looking at the vinyl records in the apartment, he places his uzi down with the butt facing the camera. In the next shot the barrel is facing the camera, and switches back again in the next shot.
Continuity mistake: In the scene where Mathilda returns to her apartment and takes the hidden stash of money out from the loose floor board, she leaves the board open and also takes the money out of the plastic bag and leaves the bag on the floor too. In the next shot, the camera angle switches to her looking down the hall because she hears people coming. When the camera switches back to the original angle of her scurrying away, the floor board is back in place and she's wrapped the money back up in the plastic - nowhere near enough time to do that. (01:02:25)
Factual error: The grenade that the SWAT team fires in the hotel is supposedly a smoke bomb, but it is both marked ILUM and has a white body, meaning that it is an illumination grenade.
Continuity mistake: When Mathilda spends her first night at Leon's apartment, Leon places a messily folded blanket on her in one shot. The camera then goes to a different shot of Leon, and then back to the original. However, we can now see that the blanket is mostly unfolded and placed neatly on Mathilda. ..... (and little pink doll she is holding changes position). (00:37:15)
Plot hole: Towards the end of the movie, Leon dies and Mathilda heads to see Tony. Tony gives her some spending money and tells her to get back in school. The nighttime scene suggests that she spends at least part of the night wandering the streets. Presumably at daybreak, she takes the tram car and returns to The Spencer School, where she talks to the school administrator. When the administrator asks Mathilda to tell the truth about what happened to her, Mathilda says in essence, "... I lived with the greatest guy. He was a hitman, the best in town. He died this morning..." This morning? Seems more like roughly 24 hours have passed since Leon died, so what Mathilda says is inconsistent with the scene sequence. (Special note - this is from the International/extended DVD edition. I can't say whether this exact sequence is in the shorter domestic DVD version.) (02:06:03)