The Bermuda Triangle Crisis - S2-E4
Revealing mistake: When Wonder Woman drops a mine into the water, she's supposed to be dropping it into the ocean. However, you can see a drain plug of some sort in the background and the "ocean" is obviously a pool, or similar.
The Pyramid - S3-E13
Revealing mistake: As Jaime starts 'cutting' along the window with her bionic fingernail, the precut outline is quite visible from the sides, and her left hand is resting on the ledge of the first hole she cut, to give her leverage. Which would be impossible for her to do, as it's raw glass and would leave bleed marks on her hands. (00:34:30 - 00:35:20)