When Catwoman is seen from the front lying on the glass after Laurel has hit it twice with the metal bar, there is a strike mark visible just to her right at shoulder level. In the next shot, now from behind and through the glass, the strike mark has shifted to the middle of her back. Had it been in this position in the prior shot, it would have been obscured by her body and would not have been visible.
The length and styling of Tom's hair changes for one scene in the middle of the movie. Throughout the movie he sports a fairly closely cropped haircut, but in the scene directly after the sushi-restaurant he has a markedly longer wavy cut and different length and shaped sideburns. In the very next scene (bedroom) he again has the much shorter cut.
When Patience climbs the windowsill to rescue Midnight, she is on the second floor, about 25 ft above the ground. When she enters her apartment by the fire escape from the backyard, it's on the first floor, no more than 10 ft above the ground.
After Catwoman's "performance" at the jewelry heist, she wakes up on her apartment floor with a ring on the 3rd finger of her left hand. However, she doesn't put the ring on until after she finds a pile of jewelry on the bed next to her.
Before her first fight as Catwoman with the guy who tried to kill her, she jumps through the rooftops of the city and has no whip. When she gets to the bar where the thug is, she has a whip tied to her hip.
When Catwoman and Laurel are fighting in the tower, Laurel is seen to strike, and crack, the glass window Catwoman is laying on twice with the metal bar. In the next shot, when Laurel is about to strike the window for the third time, you can clearly see there are three widely spaced strike marks on the window already. When Laurel hits the glass, it creates a fourth strike mark even though it has been struck only three times.
When Catwomen steals her neighbor's motorbike she starts without a helmet. During the high speed ride we see her wearing a helmet. We also see the straps of the helmet during some closeups during the ride. When she stops we see her hands still on the handle bar but when the camera moves to her head the helmet is gone.
Ever go by a jewelry store at night? Ever see jewelry in the window? No? That's because insurance companies make them take all of the good stuff out of the windows and the display cases and store them in the safe until the next day, when they are put back on display. Which means there could be no burglary as depicted in the movie.
When Patience returns Midnight, Ophelia tells her that, "She's an Egyptian Mau, the rarest of breeds." The Mau is, in fact, somewhat rare, but there are other breeds (Selkirk Rex, Korat, Somali and Havana Brown, for instance) that are far less common. Cat Fancy Magazine lists eleven US catteries specializing in Maus. The breed was introduced to the US in the 1950s, not 1940 as mentioned in the film, although its lineage dates back well over 2,000 years - a spotted Mau like cat is clearly seen in hieroglyphs, and there is the belief it is the cross between a domestic and wild cat about 3,000 years ago.
When Catwoman encounters the thieves stealing the jewelry, one of the thieves has a Desert Eagle. The standard magazine clip for a Desert Eagle can only fit 7, 8 or 9 bullets, depending on the caliber. The thief shoots 11 bullets without reloading.
When the jewelry thieves are shooting at Catwoman in the jewelry store, they fire a total of 16 rounds between them with two shotguns, without reloading. The shotguns have standard magazines, so at most, they would have four in the magazine, and one in the chamber. Thus they could have fired ten rounds without a reload.
When Catwoman is running the chains through the Hedare trucks, she is seen feeding chain over the drive axle of a truck. In the next scene when she drives away only the front left steering tires are pulled off by the chain.
After realizing her transformation, Catwoman rides her motorcycle through the city streets at high speed. After passing through an intersection, other cars pass through the intersection at extremely high speed, revealing that the film had been sped up.