Continuity mistake: Short falls through the hole and there's a POV shot of his legs moving wildly while he cries "Help!" Then he is rescued by Willie and lifted up safely, his legs now still, and his nerves calmed. However, the very same shot of the wild legs and the cries for help from before is suddenly inserted, which makes no sense whatsoever.
Continuity mistake: In the mine, Indy fights against a bearded bad guy, who throws a hammer backwards that lands on a worker's head, knocking him out. The workers are very close together in the wide angle, then equidistant in the close-up when the hammer lands, and then together again in the wide angle. Also the worker that falls unconscious is standing straight a frame later.
Other mistake: In the spike room, you see Shorty step on the switch that seals the two doorways. During that part, you see the stone extend from the wall, which he leans against to start the lowering ceiling. However, when Willie enters, without stepping on the switch, she pushes the stone to both seal the doors, start the ceiling lowering again, and extend the spikes. Why did it come out without anyone stepping on the switch beforehand like it did previously?