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)
Continuity mistake: Near the end when Kate Capshaw, Harrison Ford, and the kid are on the bridge, Harrison cuts the bridge with a large sword. Several men fall into the water below. The bad guy grabs hold and hangs on to some of the henchmen. The number of henchmen changes between shots. Close-up 3, wide shot 2, close-up no men, then back to 2 and so on. The bad guy throws some off as he climbs up the bridge but the number changes in the wrong order.
Continuity mistake: Before the first guy is lowered into the pit, the leader of the group is taking out his heart. Before he takes the heart out it is his real body, but when he is taking it out it is blatantly a model, as it doesn't have the same amount of hair and is a different colour. (01:00:10)
Continuity mistake: On the bridge scene Indy's sword changes. Initially, he has a sword with a straight blade and no hilt; however, when he shouts at Mola Rom, he has a something like a cutlass curved blade and heavy handguard to a machete-like weapon he uses to cut the bridge. (01:38:05 - 01:38:55)
Plot hole: Mola Ram has his men knock over a vat of water in a last ditch effort to kill our heroes. First of all the vat can't be that big if it can be knocked down with a few sledgehammers. Secondly, for the amount of water that chases Indy and co. down the vat would have to be big enough to fill the room it's in, which obviously it's not. Third, Indy and co. travel through several large caverns during the mine cart chase, caverns that could easily swallow up any of the water flowing through the tunnels so there shouldn't be any water left to catch up to Indy by the time they stop.
Factual error: The British / Indian troops at the end of the movie are using Lee Enfield no4Mk1 rifles. These didn't go into production until 1940. Also India never used the no4Mk1, they used the no1Mk3 until the 1950s.
Continuity mistake: The jet of water comes out through a squared hole on the rocks, and seconds later comes through many other places, making the first hole much bigger, and making pieces of rock fall off. However, when Indy cries, "Let's meet up at the bridge!" there's an aerial shot of him climbing and the mountain has the very same perfect structure as before the jet of water burst.
Continuity mistake: When Indy fights the two guards before the bridge scene, the sequence is all off. He knocks one to the ground, who lands still clutching his sword. The other one has his sword whipped away from him - it flies over the cliff, and he runs off, whimpering. We then see the other guard approach, and suddenly Indy's standing over an unconscious guard by the boulder and clutching a sword, both of which have appeared from nowhere. (01:37:25)
Continuity mistake: When the fuel runs out, the engines die and propellers stop. They are stopped as it grazes the mountain peak. In the next two outside shots as they exit the plane, you can see the propellers are again at full speed and can hear the engines. (00:16:55)