At any point after the initial 32 prints were sent out they could have made changes. Fox struck only 32 prints of Star Wars for May 25, 1977. It's alleged that of these 32 prints some were missing the footage. Look at The Empire Strikes Back. When it rolled out the 70mm prints were slightly different from the 35mm prints. Although good old George send them out as "Finished" and the 70mm prints were made he decided to go back and make some minor changes to the movies before the 35mm prints were struck. Who's to say that the 8 70mm prints of Star Wars were the exact same as the 24 35mm prints. Mr. Lucas could have very well made last minute changes or perhaps it was a lab mistake. Out of the about 1,000 or so prints of Star Wars that were out there in it's initial run (May 25, 1977 to June 20, 1978) the first 8 70mm prints may have very well been different from all the others. And those initial 24 35mm prints may have been different from all the later 35mm prints that were made on and after May 25th.