From The Godfather Legacy:

Coppola went to Italy, but with only a skeleton crew....[T]he studio wouldn't cover the costs of sending Dick Smith along to handle makeup. As a result, the work was turned over to a local Italian makeup technician. Although there was no impact on basic makeup, Pacino's makeup suffered. At that point in the film, Michael's broken jaw was still healing, so Smith created a foam latex appliance that suggested the slight caving in of the cheekbone. Smith sent the appliance, along with instructions, to his Italian counterpart but Smith said it didn't look like the application was used. It seemed as if the cheekbone had simply been smudged to give the impression of bruising. "It was pretty awful makeup," Smith said.

I agree with Dick Smith. Besides Brando's makeup being a masterpiece, the foam latex swollen cheek he created for Al Pacino was flawless. Watching the scenes in Vito's study and Louis' Restaurant, Michael's makeup defies detection.

What a shame the studio bean-counters wouldn't pay for having Smith along for the Sicilian scenes.

Signor V.