Audio problem: Knox is thrown from the hood of Vicki's car into a pile of garbage. He cries "No, no, no." He is obviously dubbed, as his cries continue briefly after he has already landed in the garbage.
Continuity mistake: The clown balloon was swelling with the Smilex gas, but when Batman steals it and flies it and the other balloons away, it's back to normal shape.
Continuity mistake: In the scene where the joker fires at Batman using his extra long gun, the barrel is straight and solid, yet when he is forcing Vicki up the Cathedral steps, he collapses the gun into a pistol.
Factual error: The Bat signal at the end would not show up like it did in the film. In order to be as clear as it was, as well as visible, it would actually have to shine onto a surface, not just the clouds. They made this same mistake in Returns, but made it believable in the clouds (just not as sharp) in Forever.
Continuity mistake: Before and after his transformation, the Joker a.k.a. Jack Napier, has brown eyes, but in the flashback, he has blue eyes.
Continuity mistake: When the man is knocked out in the alley he changes positions between shots.
Revealing mistake: In an overhead shot, just before Jack Napier falls into the vat of chemicals, you can see that it is a stunt double, as he has significantly less hair on the top of his head than Jack Nicholson.
Continuity mistake: Notice The Joker's chin in the bell tower. It's covered in blood when first shown, a shot later it's suddenly just the center of his chin.
Other mistake: A lady is looking / smiling straight at the camera and crew at the start of the film when a character is trying to get a cab.
Continuity mistake: While Vicky is talking with Bruce at the Batcave she has some tears on her face which disappear between shots.
Continuity mistake: When the Joker is giving the money to the people a bill sticks on the top side of the throne which disappears and reappears between shots.
Continuity mistake: While Bruce is talking with Vicky at the Batcave he is clean shaven, but after he attacks Axis chemicals he has some stubble on his face.
Suggested correction: The balloons were not filled with Smilex gas. The Smilex was in canisters that are visible underneath the balloons. The balloons themselves could have expended and contracted due to varying air pressure.
wizard_of_gore ★
Yes the canisters were on the underside. But if you look closely, when activated, the balloon began to swell, and holes appeared, releasing the gas.
Movie Nut