Has an Olympic Basketball (Men) game ever ended 78-56?
Exactly once. On January 1, 1956, Chile beat Australia 78-56, and no Olympic Basketball (Men) game before or since has ended that way. When it happened it was a scorigami, the first 78-56 in league history.
That makes 78-56 the 126th most common final score out of 698 that have ever occurred in Olympic Basketball (Men). One point away, 79-56 has happened never and 78-57 has happened never.