Continuity mistake: When Selina electrocutes Max while kissing him his head is tilted to the right. Shot changes and it's straight.
Character mistake: Penguin shouts, "I am not a human being! I am an animal! Cold-blooded!" Penguins are actually warm-blooded.
Continuity mistake: When the Penguin hooks the umbrella on Cat Woman he turns to our left to watch her fly away. A shot later he is facing straight, but a shot later he has suddenly moved 2 meters to the right and is facing the right side.
Continuity mistake: After The Penguin dies Batman's car drives next to a white car with its windshield covered in snow. From the shot inside Batman's car the snow is gone.
Continuity mistake: When the clown lies unconscious there's a string several centimeters behind his head. A shot later his head is on top of the string.
Continuity mistake: When Selina is about to taser the clown she puts on an evil face, but a shot later from a different shot she is staring with a calm look.
Continuity mistake: When Selina watches the clown's hand holding the taser, his fingers are clinched around it. A shot later his index finger is sticking out.
Continuity mistake: When Batman talks with The Penguin, before Catwoman arrives, The Penguin's left arm is raised or not depending on the shot.
Continuity mistake: Catwoman turns the microwave dial to the right, pointing in a 3 o'clock position. A shot later it points in a 12 O'Clock position. (00:56:04)
Continuity mistake: Inside the cage, Max covers his mouth with his hand and then uncovers it and grabs an iron bar. A shot later he is suddenly covering his mouth again. (01:37:16)
Revealing mistake: When The Penguin controls the Batmobile, before it crashes against a car on the left and sends it flying away, check the car's rear wheels: they're not touching the road.
Continuity mistake: While arranging the plan with the clowns, the Penguin throws his clothes on the floor, which change positions between shots. (01:29:23 - 01:31:00)
Continuity mistake: When Bruce goes to gear up to rescue the Ice Princess, there are visible footprints on the drawbridge that leads into the chamber where all the bat suits are kept. When he then steps back out in his Batman attire, the drawbridge is now clean of all prints. (00:00:24)
Continuity mistake: After dumping out the sewing kit, Selena picks up a pair of scissors with blue handles. When the camera is in a closeup of her, the scissors have pink handles.
Character mistake: Bruce Wayne talking to Selina Kyle says that Batman probably saved millions of dollars in property damage alone. When Batman first saw Catwoman he didn't do anything to prevent the property damage before the explosion that she caused.
Continuity mistake: When the circus gang first attacks, after Batman uses his Batmobile to take out of the two juggling guys on stilts, he opens this flat panel on the passenger side of the Batmobile to take out one of the skull mask wearing bikers. Before taking out of the second biker, he opens that same panel again.
Continuity mistake: The Penguin is getting vegetables thrown at him after Batman jams his speech on the steps. In certain angles he is closer to the banners behind him, while further in others.
Continuity mistake: Towards the end when Bruce takes the cat, the wounds on his left cheek change from faded to fresh.
Deliberate mistake: After Batman destroys The Penguin's controlling system and breaks the TV screen he is 4 meters away from a narrow alley. Shot changes and he's now downtown driving around the city, Then there's a POV shot of him driving towards the narrow alley again, though he is now many meters behind. Then back to shots of him driving downtown until he finally arrives at the narrow alley. It adds up for pace, but it's very awkward indeed.
Continuity mistake: When Catwoman exits Schreck's she's doing flips without hells. After the explosion, when she climbs the wall heels appear.
Answer: It isn't. If you look at when he dies you will see that he has cuts on his face that are bleeding red. The blue liquid is more like a bile, probably similar to saliva.