The Godfather: Part II (1974)

Other mistake: When young Vito Corleone shoots Fanucci in the chest at the doorway to his apartment, in a continuous shot, a wound/blood bursts from Fanucci's white vest. When Fanucci proceeds to tear his vest open seemingly in disbelief he has been shot, there is no entry-wound, blood or hole in his white shirt directly under where the wound appeared in his vest.

Michael Corleone: I know it was you Fredo. You broke my heart. You broke my heart!

Trivia: At Michael's hearing, very few of the senators, judges, etc. are actually actors. They are friends, acquaintances, and family of various members of the cast and crew.

Question: Why did Willi Cicci testify against Michael in court? Michael didn't do anything to Willi. In fact he even took part in the assassination of the other 4 families on behalf of Michael.