Continuity mistake: At the very end of the movie, when they all ride off through a tunnel, you can see all sorts of tassels hanging off each of the horses. When they reach the end of the tunnel and are riding off into the sun, there are no tassels at all apparent.
Other mistake: During the airplane chase Indy is seen firing his revolver at the German planes, after he crash-lands he pulls his revolver and breaks open the action to check if he's got any ammo left. He doesn't, but the issue is that a revolver doesn't eject spent shell casings, and there aren't any empty casings in his revolver, despite him firing his gun earlier and having no chance to empty the casings since.
Other mistake: When Indy is atop the tank with his father, he is facing his father. Suddenly, they show a close-up of Indy's face, head-on, with the Nazi leader behind him swinging a shovel towards Indy's head in the background. Indy gasps, and ducks. How did Indy see the shovel being swung at his head if it was completely behind him?"
Factual error: In the 'The Last Crusade', the Germans and their lackeys use MP 38 or MP 40 submachine guns extensively. The MP 38 was still a new weapon in 1938, and not around in such large numbers to arm each and every soldier with it (total of 1 million MP38/40's vs. more than 20 million troopers in WW2).
Chosen answer: They're not, no. An individual doesn't become immortal after one drink - it requires them to drink regularly in order to remain alive. So neither Jones has been rendered immortal, merely healed of any wounds that they might have. But your surmise is basically correct - as the Grail cannot leave the shrine, any individual wishing to use it to prolong their life must stay there if they wish to enjoy its effects.
Tailkinker ★
Also, in Indiana Jones and the Kingdom of Crystal Skull, Henry Jones, Sr has passed away before the start of the story and therefore was not immortal.
raywest ★