Visible crew/equipment: By the cliff, Indy's hat comes rolling towards him. Watch closely and you'll see a long shadow a meter above the ground, parallel to that of the crew member throwing the hat.
Other mistake: In the scene with the tanks, Indy rides up beside one with a rock. Watch the gun closely. The end of the one that he is supposed to shove the rock into is wobbling inconsistantly with the rest of the gun, or the tank for that matter.
Revealing mistake: When the VW gets stuck on the front of the tank and is shot off, you can see that the car has no engine, no body in the car, and no clutch. Also, when the car is blown away you can see a wire used for the stunt fall right in front of the camera.
Continuity mistake: The back of the boat gets chewed up by the prop in the same place twice.
Revealing mistake: When the car is chased by a plane and enters a cave, check the rocks above the entrance and you'll notice that both the entrance and exit are the same location and the final shot has been flipped.
Factual error: When the soldier from Hatay attempts to pass through the booby trap and his head is chopped off there is no blood. Any wound to the head or neck tends to bleed profusely but the head rolls by without a drop.
Revealing mistake: At the end a shadow appears on the cliff under Indy's shoe when he steps to the edge. This would not have happened if a solid but camouflaged bridge were there. (01:47:30)
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.
Other mistake: In the motorbike chase scene there is a lot of flying road dust even in front of the bike in the lead. Probably from the camera vehicle.
Visible crew/equipment: When Indy Sr. is shot, two big stage lights are reflected on his glasses.
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.
Revealing mistake: In the temple, when Indy walks on air, he briefly becomes semi-invisible due to the matte effect.
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.
Other mistake: After Young Indy runs out of the cave with the Cross of Coronado, when he whistles for his horse and jumps down, note the horse's facial marking and leg marking. When Indy mounts the horse it's a different horse, note its markings, and as he rides toward the circus train the horse has changed again. (00:04:55)
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.
Revealing mistake: Just after Vogel is thrown out of the blimp, in the shot of him shouting towards it whilst it is taking off, it is apparent that the sky and blimp shown in the background behind him are a projection. (01:13:20)
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.
Revealing mistake: When Indy kicks Kazim's partner out of the speedboat, the man grabbing Indy's body from behind is not Kevork Malikyan. (00:39:15)
Answer: The implication is that disaster would follow them outside of the cave as well. It wouldn't make much sense if you could simply outrun the disaster.
BaconIsMyBFF
"Followed by disaster" is a kind of curse, a thing not common in Christianity. It doesn't make much sense anyhow. A seal is just a dot - OK, so let's at least grant that the seal represents a circle that the grail has to stay in. Who decided where those borders are? The grail was taken there during the first crusade. That was closer to 1938 than it was to 33 AD. The three knights could move the grail about then. Why not afterwards? The knights could have built the traps. But the borders could only have been set by god, in an unusually late and completely atypical miracle.
Spiny Norman
There are several examples of curses in the Christian Bible: Lot's wife is turned into a pillar of salt for looking back at Sodom, the plagues visited upon Egypt, Adam and Eve are cursed for eating fruit from the tree of knowledge, etc. The knights did not move the grail around after finding it, they stayed in the temple for 150 years and then two left leaving the third behind. The great seal and it's restriction was already in place when the knights got there.
BaconIsMyBFF
Where in the movie is that stated? I interpreted the knight's story as them having made that place. Looks like it isn't actually specified. But if God made it, then I submit that he would have used Greek, not Latin, for the stepping stones. (All of those curses are from the old testament. The book where god kills firstborn children as long as they're Egyptian. Grail is by definition new testament where you turn the other cheek. There simply are no curses in the gospel, that's just not how Jesus rolled).
Spiny Norman
The tests were made by the knights, but the seal had God's power in it. Just like the cup.
lionhead
It's still a bit dodgy. What if you take a shovel and dig yourself a back door? Basically this film really excels at stuff that makes no sense but helps the storytelling, or to be precise, creates dramatic effects.
Spiny Norman
Every fictional story is like that in some way. That's why it's called fictional. It's just a story.
lionhead
Not a particularly convincing argument, "stuff happens for no reason all the time", if I may say so. Why is this website even here then? The fact is that some stories are more coherent than others. (♫ "In olden days, a hole in the plot, would seem to matter, quite a lot. Now heaven knows, anything goes..." ♫);).
Spiny Norman
It's the difference in what story they want told. Is it a fairy tale or based on actual events? A huge difference in plausibility between the two. The site is there to look at mistakes, not how believable the story is.
lionhead
It is not set in another universe so plausibility isn't somehow suspended. Maybe take a look at the categories recognised by this website. Plot holes, factual errors, even stupidity. (They? Who are they?).
Spiny Norman
It is set in a fictional universe because it's not a true story. With "they" I mean the writers/director. Mistakes in a plot (plot holes) have nothing to do with how believable the story is. As long as it's plausible, it's not a mistake.
lionhead
Pretty sure it's the same universe, just with some added characters/events. What about the total lack of spaceships or orcs or talking animals for example? The seal business is not a mistake YET, but it's very dodgy because no-one knows how it works or why. Like all Indys "trapped" secret places, it's (among other things) unclear who resets the traps for the next visitor. We can't brush it ALL off as "the hand of god" every time.
Spiny Norman
Huge amounts of stuff in films isn't exhaustively explained. Doesn't mean there isn't an explanation that's perfectly believable. There's zero evidence either way to say how "followed by disaster" would manifest, and just because there's not a thorough explanation doesn't mean that it's "dodgy", and it's not worth bickering about either, because there's no concrete answer either way.
Jon Sandys ★
OK but I would like to note that not everyone who offers creative explanations has recently seen the movie; some people just invent their own. E.g. "followed by disaster" is not an actual explanation from the movie, it was just one of the suggestions made here and only here. Or the ones on my own question below. All I'm saying is, it's very hard to tell what the "rules" / "logic" of this place are supposed to be, so I understand what the OP was driving at.
Spiny Norman