The Godfather: Part III (1990)

Continuity mistake: When Mary is hit at the end of the film and Kay screams, Vincent looks up and shouts "No!" and the scene cuts back to Michael holding Mary, as we hear Vincent continue his line ("Mary!") but then Vincent appears behind Michael and Mary, walking slowly up the steps, hair slicked back, gun in hand, mouth closed as his line is still being delivered, with no pause ("Mary! No!"). The next cut shows Vincent back at the bottom of the stairs near the priests, with his hair mussed up. And the poor editing continues - when the camera pans out following Michael's scream, we can see Vincent slowly walking up the steps behind Michael, and this is the same shot as before from a different angle.