• Continuity: Eckhart's beard when he busts Jack raiding the office.
  
  
• Continuity: A Smith & Wesson turns into a Colt on the fight on the catwalks.
  
  
• Continuity: The name of the museum is spelled differently on the outside and inside.
  
  

• Continuity: Pink handprints on a canvas in the museum.
  
  
• Continuity: The Joker knocks over a statue in the museum that soon rights itself.
  
  
• Crew or equipment visible: When the Batmobile first drives itself automatically, a hand is visible on the steering wheel through the tinted windscreen.
  
  
• Continuity: Batman's communicator after telling the Batmobile to stop.
  
  
• Revealing mistakes: After the Joker has killed Grissom, we see his hand move.
  
  
• Continuity: The port gun door on the Batplane opens twice.
  
  
• Continuity: Tables and chairs vanish after Alicia enters Grissom's meeting.
  
  
• Continuity: The shape of wiped-off makeup on the Joker's face changes.
  
  
• Revealing mistakes: When we first see the Joker as he confronts and kills Grissom, he comes out of the light and a large purple splotch appears on his neck. On the Special Edition DVD of the film, the make-up adviser explains that this was done because some of the white make-up used for the Joker's face got on the coat collar, and rather than taking it off with alcohol, they covered it up with purple shoe polish.
  
  
• Revealing mistakes: During the parade scene when Joker releases the gas, Vicki escapes harm by entering the car. When driving away you can see that the rear passenger side window is open.
  
  
• Revealing mistakes: When the Joker releases the gas during the parade scene, Alexander Knox takes a white dust mask out of the car to prevent him from inhaling the gas. A dust mask only protects you from dust particles and not from gas.
  
  
• Factual errors: When Batman goes to blow up Axis Chemicals, he uses pop-up machine guns to cut down a door. We see the guns bouncing up and down with the recoil and with the swaying and bumping of the car, but we the bullets still cut a straight clean line without any stray bullets.
  
  
• Continuity: Vicki Vale wears high heels for most of the film but when she stands on the grated floor in the Batcave she's conveniently wearing flat-heeled shoes. Later on she hasn't changed her clothes but she's wearing high heels again.
  
  
• Continuity: The balloon behind the Joker's car (the clown balloon) is close to the ground on close-up shots, and floating high from the ground on other shots.
  
  
• Continuity: Blood on the Joker's chin vanishes in the final scene.
  
  
• Continuity: When destroying the paintings in the museum, one of Joker's henchmen puts several hand prints on a painting. Later, we see Joker imitating the statue, and in the background we can see the painting that had supposedly been fingerpainted is not.
  
  
• Continuity: Bruce Wayne pauses the video with Joker's eyes closed, but the next time we see the paused scene, his eyes are open.
  
  
• Continuity: When leaving the dining room, Vicki Vale reaches for her wineglass twice.
  
  
• Revealing mistakes: In the opening fight scene, Batman kicks the mugger Eddie through a door. While Eddie is flying through the air, the wire attached to his back is visible.
  
  
• Continuity: The list of fatal "combined" ingredients in the newspaper does not match the one read by the anchorman later.
  
  
• Continuity: Bruce Wayne is shot in the arm during the sequence with the Joker and the mimes, but a short while later there is no longer a hole in the sleeve of his coat.
  
  
• Revealing mistakes: The Axis Chemical Plant iron gate opens a little bit before the Batmobile smashes it open.
  
  
• Revealing mistakes: When stealing the Jokers balloons, Batman hits a number of switches to close the claw, as he does so, three LEDs go off, one of them (the red one) clearly marked "volume".
  
  
• Continuity: The Joker and Vicki Vale are alone as they ascend the Bell Tower, but when Batman follows them up, he is attacked by a couple of the Joker's men.
  
  
• Errors in geography: The film is set in Gotham City, USA, but the bottle the Joker holds up in his "Smilex" commercial is for a "Moisturising" creme (instead of "moisturizing"), a tip-off that the bottle was created in England, where the film was shot.
  
  
• Errors made by characters (possibly deliberate errors by the filmmakers): On the newspaper that explains the combinations of dangerous products, Odor Eaters is spelled "Odoureaters" (UK spelling in the USA). In the same piece, the first combination is "Deodorant's with Baby Powder" (misplaced apostrophe).
  
  
• Revealing mistakes: When Joker points the gun at Bob to shoot him, Bob jumps before the gun is fired.
  
  
• Continuity: After Jack takes the axe and smashes it into the acid vat, we see the acid on his jacket (very visible when we see him running up the stairs to escape the police shooting at him). But when Jack is on the catwalk, with his back to the camera, his coat is perfectly dry.
  
  
• Continuity: We are led to believe that Vicki Vale has just moved to Gotham City, yet the Joker asks Bob to get her number from the phone book, which would obviously not include it yet.
  
  
• Continuity: When Bruce is examining the plate in Vicki's apartment, an indentation is visible before the Joker shoots it.
  
  
• Revealing mistakes: When the Bat-Signal is shone into the sky, the "sky" moves, revealing the sky to be a backdrop.
  
  
• Factual errors: The Bat Signal at the end of the film produces a nice, clean flat image against the sky. A lighted signal such as this, however, would need a backdrop to be cast against to be seen (clouds, for example.)
  
  
• Continuity: When Batman captures the balloons with the Batwing and sets them free, they are clustered together. In the very next frame, they have spread out.
  
  
• Continuity: When the Joker pursues Vicki in her apartment, at one point she grabs a popcorn dish from a shelf. The dish in her hands appears and disappears between shots.
  
  
• Revealing mistakes: When Batman enters the museum from above by breaking the ceiling window, a cable can be seen as he descends.
  
  
• Revealing mistakes: Obvious animated "stand-in" for the Joker when he falls to his death.
  
  
• Revealing mistakes: When Batman climbs out from the wrecked Batwing, he climbs out from the rear of the plane - obviously not the cockpit he was flying from.
  
  
• Continuity: When Batman piloting the Batwing takes off with the parade balloons. At first there are only four balloons. In a wide shot, five balloons are being carried, including the infant balloon which was seen during the Smylex gas scare. But when Batman sets the balloons free, four balloons are released, not including the infant balloon.
  
  
• Continuity: Vicki Vale and the Joker are ascending the stairs of the Cathedral and the shoe slips off of her left foot but when it lands it is the right foot shoe.
  
  
• Revealing mistakes: During Bruce Wayne's casino party, he drinks champagne just after meeting Vicki Vale. Though he seems to drink from the glass, it is obvious that it is completely empty.
  
  
• Continuity: When the Joker is at City Hall with his mime gang, the mime gang opens fire on everyone around. In one shot, two police officers are at the top of the stairs of City Hall, but in the aerial shot, the police officers are gone.
  
  
• Continuity: During the Joker's Parade, one of the dollar bills that his goons were throwing out to the crowd gets caught on his throne. However, when he tells his goons to put on their masks, it has vanished. It reappears when the Joker pulls out the remote control.
  
  
• Revealing mistakes: When Batman punches the Joker and he falls over the Cathedral ledge, the mat on which the stuntman fell on is visible on the left of the screen for a split second.
  
  
• Continuity: When the Joker is throwing his parade, the float that the Joker stands on passes the same building (marked delicatessen) twice.
  
  
• Crew or equipment visible: When Batman saves Vicki from the museum you can see a crew members hand holding Vicki when Batman raises them up in the air.
  
  
• Continuity: After Batman blows up Axis Chem. he is standing in front of the car as it stops. When the Joker arrives in the helicopter he shines a light at Batman. Then they cut to a shot of the copter leaving with the light off, but when they cut back to Batman it's on again.
  
  
• Revealing mistakes: As Batman and Vicki hang from the ledge atop the Cathedral, Joker dances around, causing the "stone" parapet to wobble.
  
  
• Continuity: In the flashback the young Jack Napier has blue eyes, but the adult one has brown eyes.
  
  
• Revealing mistakes: When Batman drops into the museum on Vicki and the Joker, the wire attached to his left side is visible.
  
  
• Continuity: Vicki has nothing in her hands when being rescued from the museum but she somehow acquires a huge camera during the getaway and is able to take all of the pictures of the fight in the alley.
  
  
• Revealing mistakes: During the fight in the alley after the chase, a goon with two swords appears, and Batman knocks him out. The actor in the Batsuit is clearly not Michael Keaton - the jaw is slightly offset. After this, it is Keaton again.
  
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For instance when Batman desends from the roof of the museum you can clearly see a cable, but I think it was Batman's cable, otherwise he just jumped from about three stories up.  Or the one that says you can see a crew member's hand helping Vicki up in the same scene, I'm pretty sure it's Batman's hand around her waist.