Revealing mistake: When Robin is being pulled underwater by Ivy's plants he surfaces for air and gets pulled under again. It's obvious the film was just rewound. Then when he finaly gets free we see the shot that was rewound was the same shot used when he escapes. Really bad editing. (01:34:50 - 01:36:40)
Revealing mistake: When Freeze is freezing the town, the cop car that crashed into the store has flexible icicles on the driver side door. Also when the city is being defrosted, when the cop comes out of the car, the icicles are very wobbly. (01:38:15 - 01:48:15)
Revealing mistake: After Arnie freezes Robin, then freezes the doorway, then wipes his hand on the ice to wave goodbye to our hero, you can see that the clear spot is there before he wipes it with his hand. (00:13:50)
Revealing mistake: In the opening heist at the Gotham Museum of Art, just after we see the large diamond soaring through the air and Batman incapacitating a goon, Robin skates over to a statue to remove its spear to use it as a vaulting pole. When he whacks the spear to remove it from its position, the icicles on the statue wobble, just like fake rubber icicles. (00:08:20)
Revealing mistake: When Poison Ivy and Bane take over the street gang's lair, they try to take down Bane by wrapping chains around his arms. As he throws them over his head, one of the thugs still attached to their chain causes Bane to move backwards slightly. Kind of unlikely considering how strong Bane is. (00:57:40)
Revealing mistake: In one scene where our heroes are defrosting Gotham city using the sunlight, we see Commissioner Gordon stepping from his car which has been covered in flexible icicles.