Continuity mistake: When the boat scene starts, Indy passes by an iron tower. Then he stands to fight the baddie and the boat passes by the tower again.
Continuity mistake: Henry pulls up Indy with both arms, but when the shot changes he is pulling him up with one arm only.
Continuity mistake: When Indy is in the cliff reaching for the grail, his hand swaps between clean, dusty and sweaty, between shots.
Continuity mistake: Henry tells Indy "let it go" and Indy takes his left arm to where his father is. Half a second later his arm is away and he repeats the previous movement.
Continuity mistake: When the grail falls down the cliff and Elsa and Indy try to grab it, the ground it lies on is either yellow or brown. This changes back and forth and has nothing to do with lighting.
Continuity mistake: When Henry surprises Marcus in the tank, there is nothing hanging out of the pocket on Marcus' suit. In the next shot, there is now a pendant hanging out of the pocket, but when Marcus shakes Henry's hand in the next shot, the pendant has disappeared.
Continuity mistake: When Indy shoots the 3 Nazis while rescuing his dad, one of them falls and breaks a bench and lands on his right side. When they leave the room, the bench is intact and he's on his left side.
Factual error: When the Nazis are meeting with the Sultan of Hatay he remarks he wants their Rolls Royce Phantom II, he quips about the size of the engine being 4.5L engine with 30HP. In reality, the Phantom II had a 7.7L I-6 engine with 40-50HP. Also, the vehicle shown in the movie is a Rolls-Royce 20/25HP Barker Saloon, not a Phantom II. It also makes little sense that the Nazis would be driving a Rolls Royce since it is a British car. In the novel, the car is said to be a Daimler-Benz, which matches what the Nazis actually used in real life.
Continuity mistake: When Indy sees Elsa losing her grip on the tilted earth and then falling on the rising ground during the temple quake sequence towards the end of the film, he lets go of his father, but when the camera changes to behind Elsa in the next shot, Indy is back holding his father again.
Continuity mistake: After young Indy escapes from the lion, when he's on the rooftop of the carriage a bad guy aims a gun at him. A shot later his arm is already lowered.
Continuity mistake: On the ship near the beginning, after Indy drops the cross, water comes up and washes it towards the edge of the ship. It goes over a lip on the deck, inches away from falling over the side. However, when Indy goes to grab it, it's not over the lip. It's half on and half off.
Continuity mistake: When Elsa picks up the Holy Grail and tries to remove it from the Temple, Henry places his tie around the collar of his shirt, but in the next shot, he is now holding on the tie and places it around the collar a second time.
Continuity mistake: When Elsa says "How dare you kiss me!" and starts kissing Indy, her hand is under Indy's ear, but when the camera angle changes to behind her in the next shot, her hand is now pressing his ear.
Visible crew/equipment: At the hotel where Indy knocks on Elsa's bathroom door, she opens it and shuts the music off. The camera pulls backward and its shadow is visible on the left side of the door frame. It's fairly large.
Continuity mistake: During the boat chase in Venice, one of the boats blows up. A small piece of it with a motor comes flying out. In the next shot which is a wide shot, that piece of boat is gone.
Visible crew/equipment: At the beach, right before Dr. Jones scares the birds there's a zoom-in close-up of his face and a crew member approaching is reflected on his glasses.
Continuity mistake: The tank turret is at a completely different angle when it shoots at Jones when riding his horse.
Revealing mistake: The seagulls on the beach (when Dr. Jones scares them with his umbrella) are blatantly fake. They don't move an inch. This was also confirmed by producer Robert Watts in this making-of video https://www.youtube.com/watch?v=BMFMKsrXuGY (minute 2'30").
Continuity mistake: Indy brings the carbon copy to Markus who says "The name of the city is Alexandreta", and a close-up shows the paper with no hands on it; a shot later Marcus' hand is on the paper.
Continuity mistake: The holes produced by the rhino's horn on the roof of the train carriage disappear in the wide shot when young Indy grabs onto the swinging pole.
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 ★