Visible crew/equipment: In the scene where Joey Zaza is murdered, one of his henchmen gets gunned down with a shotgun. Just before the blast hits him, the side of one of the wooden street stalls magically changes to a breakaway so he can crash through it dramatically, instead of just slumping down against it as he would in reality.
Continuity mistake: Mosca, the assassin, in preparing to shoot Michael Corleone at the opera house, is installing the telescope on his rifle backwards. Later, when seen aiming the rifle, it is installed correctly, but is a different telescope.
Continuity mistake: When Calo assassinates Don Lucchesi, he grabs the Don's glasses and stabs him in the upper chest about three inches below the collar of his shirt, yet later, when Lucchesi is shown slumped in his chair and bleeding, the glasses are seen sticking out of his neck above the collar.
Continuity mistake: During the scene that takes place at the party were Connie is singing the song about the instruments, Vincent Mancini and his mother can be seen arriving to find out their names have not been listed to attend. The shot switches back to Connie singing, and Vincent's mother can be seen at a table enjoying the song and festivities. It then cuts back to the entry hall where Vincent begins to shove people around, and his mom is still standing there looking upset that they have not been admitted to the affair.
Revealing mistake: Several newspaper spins show Michael Corleone in the headline, but a screen shot reveals body copy that is unrelated or outdated. For example, the headline dated 1979 has copy referring to events occurring in the 1990's. Another has body copy with instructions from a software manual.
Continuity mistake: At Michael's celebration there is a scene of a family photograph taken on the stairs of his home. When the photographer is taking the picture of the family, you can see that the camera he is using is a Sinar P1. But when the scene's angle is reversed, you see the front of the camera, and it is a completely different one - a Toyo-View G.
Other mistake: Before Joey Zasa is murdered, an altar boy in the parade (on the left side of the screen) can't help but stare at the camera all the time.
Continuity mistake: When Altobello asks a young boy in Sicily to imitate a donkey, he is served a jar of wine with the handle pointing to the left side. In the close-up it points to the right side.
Other mistake: In the Mafia World, Vincent would have never been appointed boss of a family without first being initiated as a full member of Cosa Nostra, working his way up the ladder from soldier to Capo, etc. As far as we know, Vincent, from the beginning, was only an associate working for Joey Zasa, then starts tagging alongside Michael, who gives him control of the Corleone Family later, after his failing health.
Other mistake: In the mafia world of Cosa Nostra, anyone that puts their hands on a made member, especially a low-level associate such as Vincent, would be immediately killed. Vincent would not have been allowed to live for viciously assaulting a mafia Capo, as was the rank of Joey Zasa in the film. Not even Michael could have saved him from such a fate had this been true.
Answer: It shows you how greedy they are even as they've made it to the zenith of their criminal careers. That's why you see Michael pass it on disgustedly and stare blankly into the ether. Michael's goal was never to be the boss or capo di tutti capi, he only did it to protect his father and then his family, his main goal. And at that moment he realises he's never getting out. He's a business man in a world of criminals (which he is himself).