Revealing mistake: When Gittes visits the orange grove and crashes into the tree, you can see that a steel plate has been placed around the tree to protect it.
Revealing mistake: It's supposed to be the middle of the night when Elsa disappears, but the day for night effect is lacking to the say the least; the sun glow can be seen around the building, and the perfectly white clouds when Elsa is walking through the ruins. (00:33:00)