Continuity mistake: In the library scene Indy discovers the "X" high up on the balcony. The X is green with a grey background. When he breaks the tile to find the tomb the X has become a faint outline on the floor. (00:27:40 - 00:28:45)
Suggested correction: You still can see one "leg" of the X on the floor, it's only darker than viewed from above because the camera angle and illumination set used.
I think it is meant to be an optical illusion.
The "X" is first shown as a dark green "X" on a beige background. Next, we are shown the same dark green "X" that is barely visible over a green background. I think we are meant to understand that the beige square tiles were lifted away in a cut scene.
I see no reason why they would replace the floor just for the higher shot, it's the same floor throughout the scene. When they enter it's the same floor we see later as they are going into the hole. It's probably not a real marble floor, so they can use a styrofoam or plywood tile that Harrison can lift, one that matches the surrounding tiles. They don't shine as much as the rest of the floor. In the shot up high there is different lighting, so that could explain it. It just appears to be different. Of course, sudden different light can be seen as a revealing mistake.
Suggested correction: Not a mistake, just a different viewing angle.
Continuity mistake: When Indy and gang are racing the Nazis to the canyon of the Crescent Moon, Indy looks at the Nazi convoy with binoculars. Close-ups of Indy show the sun is clearly behind him, and the binoculars are in his shadow. But then a glare from the lens alerts the Nazis to their presence. (01:24:25)
Suggested correction: It is not clear that the glare is coming from the binoculars rather than the car behind them (after all, the Nazis target the car with the tank).
They see a glare rather than a car. But anyway, regardless, the problem remains that the sun is behind the car too.
Revealing mistake: When the tank falls over the cliff and is rolling to a stop, you can see that it leaves a trail of paint behind it (a cheaply-made model, I guess). (01:36:55)
Suggested correction: It's not paint being left behind but clean dirt which has been uncovered by the rolling tank, if you look to the right there is a rock the same colour which wasn't touched by the tank.
Other mistake: On the zeppelin, Indy's dad says, "You left just when you were becoming interesting..." Harrison Ford is mouthing Sean Connery's lines. (01:14:50)
Factual error: When Indy and Marcus first arrive in Venice on the boat the dock they alight on to has tactile pavers (for the visually impaired) installed on the platform. These weren't invented until 1965, some 25+ years after the scene takes place.
Suggested correction: One piece of the pier looking different doesn't mean that is meant for blind people, could be just a repair, or decorative, or a coincidence, could be anything.
You can see it is a tactile paver as it has the raised spots.
Continuity mistake: When Indy is pouring the water from the Grail onto his father's wound, we see him pour all the water out. When his father takes the Grail, there's now water left inside.
Suggested correction: Automatic refilling seems to be the least of the miracles the Grail has performed.
There was no evidence of this, plus we never see it refill before or after. How would it be empty when they first find it if it miraculously refilled itself? This is a poor correction just to make a correction.
