I didn't notice it.
If it's the dissolve from Micheal sitting in his home office to the first shots of Vegas and the marquees, I checked it against the BD and saw no difference that jumped out at me.
Perhaps I am looking at the wrong scene?
Finally got to watch THE GODFATHER in 4k today, briefly popping in RAH's BD to do some comparisons.
Though I noticed colors are different than the BD release, the 4K transfer certainly looks beautiful with its apparent incorrectness.
The biggest problem I noticed was that grain has been...