I’ve heard that the script was changed during shooting to alter Luke’s last name to Skywalker. The revised surname wasn’t added in pickups, it was part of principal photography.

However, I’d be extremely curious to know if there was alternate footage with the original name.

There are also alternate takes several Tatooine scenes with Luke wearing a poncho, and not wearing the yellow jacket during the Yavin medal ceremony. But info about these is strangely hard to find, even when almost every other aspect of SW has been talked to death.