The end of Indiana Jones and the Last Crusade shows Indiana filling the Holy Grail with well and healing his father from the gunshot wound, followed by happily-ever-after as Indiana, his father, Brody and Sallah ride off into the proverbial sunset. A happy Hollywood ending.
However, even if one believes in the Holy Grail, isn’t there a plot hole in the script?
You have chosen wisely. But the Grail cannot pass beyond the Great Seal. This is the boundary and the price of immortality.
If immortality doesn’t extend to the outside world, how about the its recuperative powers? One interpretation may say that once Indy’s father passes the Great Seal that his health reverts and the gunshot wound returns.
Of course, this isn’t happily-ever-after, so stretch your imagination and enjoy what is an excellent and extremely fun movie.