6. Steven Soderbergh - Ocean's Eleven
The Plot Hole: Danny Ocean (George Clooney) and his men trick casino honcho Terry Benedict (Andy García) by swapping out his money with a duffel bag full of hooker flyers, but considering that this switch clearly occurs as the bags are carried from the vault to the decoy van, where the hell did the flyers come from in the first place?
The film makes it abundantly clear that there's no way anyone who enters the vault could've been carrying the flyers, and to his credit, director Steven Soderbergh totally holds his hands up in his commentary for the movie, admitting that there's no remotely plausible explanation for it.
Given that the entire heist falls apart without these flyers, and accepting how ridiculously intricate the plan is as a whole, it's pretty ridiculous that such a vital part of it was so thoroughly glossed over.