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)
Other mistake: This one is hard to describe. At the start of the movie, when Freeze and his gang are robbing the museum, Freeze looses his gun and it flies up to land on some sort of higher surface. However, it looks REALLY fake when it lands, perching right on the edge, which would be impossible for such a large weapon to do if thrown at that speed and from that angle. (00:05:25)
Deliberate mistake: When Barbara Wilson/Batgirl first arrives she is standing on a ledge beside the front door when Robin answers the door. She then exclaims, "Oh. Uncle Alfred." However she could not possibly have seen him, not just because of her angle, but also the fact it is after that statement that he first comes into view. (00:34:10)
Visible crew/equipment: Just after Robin and Batgirl have dropped down to a ledge beneath the Gotham Observatory in the final fight scene, Bane appears behind them and grabs them by their necks. You can see the light reflected from the camera crews' lights on the icy wall on the right side. (01:43:05)
Continuity mistake: In the first shot that shows a high view of Mr. Freeze standing on the stairs, his ice gun is pointed up. But, when it shows him again, the gun is resting in his hands. The next shot shows him bringing the gun into his hands again. (00:03:50)
Continuity mistake: When Dr. Pamela Isley and Bane first arrive in Gotham City and are driving to the Gotham Observatory in their (stolen) red car, Dr. Isley is putting on a wig. When she grabs the wig out of the box and puts it on her head, you can see that she has black gloves on, but the gloves are missing when she is looking in the mirror and says to Bane "Gotham Observatory, Bane. And step on it." (00:34:05)
Other mistake: Watch carefully during Freeze's opening heist: two of his goons accidentally check each other and nearly fall down. This can be seen on the left-hand side of the screen in the overhead shot (one skates next to Freeze, another skates around an ice spike) just as the camera passes a column. And where's that spotlight that follows Freeze coming from?
Audio problem: When Mr. Freeze talks about his plan to freeze the city, he yells out "It'll be winter forever here in Gotham," but if you watch, his mouth doesn't match his voice at all through the entire sentence.
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)
Continuity mistake: In one of the scenes when Freeze is going to take the diamonds from Ivy's neck, you can clearly see that he has no make-up in his neck (and it isn´t an effect of the lights, he has really no make-up). (00:45:00)
Plot hole: When Robin and Batgirl are defrosting the mirrors on the telescope, don't you think that at least some of the beams would reflect back at them?