Revealing mistake: When Indy is in the archive room cornered by the thugs, there are a couple of wide shots where it's definitely not Harrison Ford, but a stuntman with a mask resembling his face. The wide shots cut to close-ups of the real Harrison, and one can see the big difference between both. According to the making-of videos, several stunts were played using this technique.
Continuity mistake: When Helena and Indy are cornered in the archive room, Helena—in the background—rushes upstairs. A shot later, she is metres behind, arriving at the steps again and repeating all previous movements.
Answer: I remember that Archimedes gave Indy the dial, but he kept the wristwatch.
raywest ★