Continuity mistake: By the cliff, Dr. Jones hugs Indy, whose jacket is down at waist level. When Dr. Jones leaves, Indy collapses on his knees and now the jacket is perfectly placed over his shoulders.
Revealing mistake: Dr. Jones fires at the jeep from the tank, but the explosion doesn't come out the cannon, nor by the jeep's window next to it; instead the back of the jeep explodes.
Continuity mistake: The German Nazi suddenly disappears from the tank when it crashes on the ground (as is replaced by an obvious scale model).
Continuity mistake: When Indy leaves the steering wheel to stop the baddie on his motorboat, he passes by a metal turret twice in less than half a second.
Continuity mistake: During the fight on the tank, Indy punches a German who falls on the wheel and whose hat falls near the turret. When the angle changes the hat is in front of him, but when he falls off the tank the hat is gone.
Continuity mistake: The plane explodes at the exit of the tunnel. A frame later the exit is clean and the small remains are scattered around.
Continuity mistake: When Indy and Elsa encounter the rats, hundreds of them block the way, making Indy lift up his legs. However, a frame later, when Elsa starts to walk, those rats have disappeared.
Visible crew/equipment: After Dr. Jones is healed, Indy tells him to stand up. Stage lights are reflected in Dr. Jones's glasses.
Continuity mistake: After escaping from the turning blades, Indy's hat swaps from clean to filled with spiderwebs. Though there are 4 seconds in between, he didn't move from the previous spot, nor were there any webs around.
Continuity mistake: Right before the castle is on fire, there is a chair very close to the fireplace. When the place starts to burn, father and son take shelter under the fireplace thanks to the fact that the chair has magically moved several meters away.
Continuity mistake: While in the train station in Iskenderun, Marcus passes by the same spot and the same people twice (watch the man with the hen on the left).
Continuity mistake: When Donovan turns into a living corpse the badge on his lapel disappears.
Continuity mistake: When Donovan drinks from the grail his left hand holds the base with extended fingers. A frame later they are bent.
Continuity mistake: In the catacombs, Indy finds the tomb and blows dust away from the shield, cleaning the sides of the engraved cross, but leaving the rest very dusty. A frame later, the whole cross is spotless.
Continuity mistake: While the propeller chops the boat, Indy grabs Kazim and lifts him up saying, "This is your last chance." But from the opposite angle Kazim is still seated.
Continuity mistake: When young Indy discovers the thieves in the caves, the pot on the right swaps from laying horizontal on the ground to slanted and back to horizontal, depending on the angle.
Continuity mistake: Young Indy grabs the Coronado cross, but from the next angle his hand is away about to grab it, and also its position has changed.
Continuity mistake: When young Indy says, "Cortés gave away the cross in 1920.", the thief is holding it with both hands. A frame later he holds it with just one hand.
Continuity mistake: When Indy escapes out of his office through the window, there are no shadows around. Half a second later, from a different angle, two long shadows have appeared underneath the window.
Continuity mistake: When Indiana's dad blows up the truck beside them during the chase, there's a big explosion. However, in the next shot showing Indiana and Ernst Vogel, the same explosion behind them is smaller.
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 ★