Continuity mistake: When Elsa is looking out over the Canyon of the Crescent Moon, the sun is low - it is close to sunset. However when Indy is riding through the very narrow canyon, the sunlight reaches the bottom. It is not the same time of day (or later the same day).
Continuity mistake: When Senior is rescued from the tank with a whip around his ankle, the whip dissappears a split second later, when he is being mounted on the horse.
Continuity mistake: When Indy is rescuing his father from Brunwald castle, he uses his bullwhip to smash through the window of the room his father is kept in...but in the time it took to jump into the room and get smashed over the head by his father, the bullwhip he used would have lost lots of its momentum and it wouldn't be waiting for him to grab it and use it later on the movie. (00:47:40)
Continuity mistake: During the big chase scene leading up to the three challenges, Indy uses his gun and begins to takes the high road on his horse. Harrison Ford couldn't seem to find the holster for his gun, so you can see his holding the gun by his side until the scene changes. (01:31:15)
Continuity mistake: When they are first looking over the cliff at the tank, Sean Connery's beard is quite full, and in a shot moments later, still looking off the cliff, it has been trimmed.
Continuity mistake: The back of the boat gets chewed up by the prop in the same place twice.
Continuity mistake: After Indy exits through the sewer with his hair all wet, he escapes Kazim's men. When he turns around a block his hair is nicely combed and loose, instead of sticky. Not too plausible when you're running for your life and your head is soaked in petrol.
Continuity mistake: The distance between Indy's boat and the big red and white ship keeps increasing and decreasing randomly.
Continuity mistake: In the zeppelin, after Indy says "no ticket", everyone searches for their tickets and waves it at Indy. When the angle changes, a frame later, the people are searching for their tickets, no one is showing one.
Continuity mistake: The crater Indy's car falls into becomes bigger and way deeper between the first and second shot.
Continuity mistake: When the driver of the tank is shot and he changes the direction of where the tank is going, Indiana gets up, with his strap still stuck on the nozzle. However, in the next shot, he's become clear of being stuck. There's no way he could have gotten his strap undone so quickly.
Continuity mistake: Near the end, in the "Leap of Faith" scene, Jones steps off the edge of the abyss and discovers an ingeniously-camouflaged stone bridge. The camera pans to show the camouflage effect from another angle, and it's obvious that the stone bridge is only about one foot thick from one end to the other. Relieved, Jones scampers across to the other side, and the camera cuts again to show that the bridge is now a full three feet thick.
Continuity mistake: Before the propeller chops the boat, Elsa leaves and looks at Indy. Right then, the camera is reflected on her boat's windshield.
Continuity mistake: Indiana has his satchel on him at the beginning of the 3 challenges and up to the point when he is entering the resting place of the grail. As soon as he enters the cavern where the Knight is, and he stands up, he no longer has the satchel.
Continuity mistake: Young Indy escapes from the four diggers, and you can see them exit the cave after him as he pauses. He moves down to and jumps onto the horse (missing the first time). He gets on the horse and you see the diggers, starting running from the exact same place that they were. It's like they paused their pursuit while the camera was not on them. If they kept running, they would've easily caught up with him before he jumped down.
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: 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.
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.
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