Revealing mistake: Indy's bridge breaks and he is hanging by it with the natives shooting arrows at him. If you look closely you can see two arrows bounce off his back. All the other clatter noisily onto the cliff-face or stick in the bridge, so it's not like they've lost much force due to the range. (01:48:40)
Revealing mistake: When Indy and Willie jump out of the Obi Wan Nightclub, they fall through several awnings, the idea being that they will break the characters' fall. All well and good. But, if you look very carefully, you can see small taped-up cut marks which the crew made so the stunt men (and women) could effortlessly glide though the awnings.
Revealing mistake: During the mine cart scene, after Indy notices that the track cuts out, just as the mine cart flies over the expanse there's a vertical wire at the back of the cart, leading up to the top of the screen, and a horizontal wire at the front of the cart, leading toward the right side of the screen. Additionally, when the mine cart lands on the other track keep your eye on the top edge of the screen as something dips into view, but it's pulled back up immediately, right before the shot cuts away to Mola Ram. The wires and the mysterious object can be seen when viewed on Amazon Prime, but they seem to have been edited out of the DVD (2008 version) I own.
Revealing mistake: During car pursuit, when the Chinese thugs drive into the food stands and two of them fall onto the tables, you can see that at least one of them is a puppet from the way his arm is rigidly sticking out when he has fallen. It should have fallen to his side. (00:11:45)
Revealing mistake: When the water floods the mine, some shots of the 3 heroes are an obvious composite of their blue screened image over a set. Problem is, when Indy tells the two to run towards a tunnel on the right with a log blocking the way, Indy and Shorty run through the log as if they were ghosts.
Revealing mistake: When Indy is hanging on the cliff as it falls out from underneath him (right after the mine cart scene), as he's kicking, you can see the stone wall moving in and out as he hits it after the rocks fall out underneath him.