Revealing mistake: When Batman drives the Batmobile into the Axis Chemicals factory, watch closely when he slams through the first gate - you can see the gate is swaying and starting to open before the batmobile hits it, indicating it wasn't really closed and was left unlocked and partially open to make it easier for the stunt-driver to drive the Batmobile through it.
Audio problem: Unlike the second movie, the jet engine sound was not dubbed over the piston engine sound. The fact is, the jet engine in the Batmobile is a fake.
Revealing mistake: When the Batjet crashes, if you pay close attention to the scale of the jet, cars and buildings in relation to the scale of the fire and explosions, it is very clear that this scene was created with models.
Revealing mistake: When the reporter dies on air, her face is contorted into the Joker's face. When the camera is in closeup on her face, the "dead" woman's bottom lip moves.
Revealing mistake: When Jack falls into the chemical vat it's obvious the vat is quite shallow as he doesn't actually sink into the chemicals but instead just kind of lands and then sits there as liquid splashes out around him. To top it off, the subsequent shot of him disappearing into the chemicals is reversed as several bubbles can be seen 'unpopping' and growing smaller.
Continuity mistake: When Batman and Vicky are running from Joker's museum plot, and are running from Joker's henchmen, he shoots a cable up to a walkway. As the camera shows him firing, he fires the rope at a 45 degree angle, yet when he and Vicky are going up on the rope, the walkway is directly above them and the rope is perpendicular to the ground.
Revealing mistake: In the film's ending shot, the sky can be seen to flutter as the camera pans up, revealing a backdrop.
Revealing mistake: When Batman fires rockets at the Joker, none come out, instead a sound effect is used which cuts to explosions on the road where Joker stands.
Audio problem: Bruce watches Commissioner Gordon on tape at his party. In the first part, the audio is laid wrong and their mouths don't match.
Revealing mistake: When Vicki is driving car Knox jumps on, you can see it's a stunt driver in the wide shots.
Continuity mistake: When Joker comes to Vicki's apartment, Joker shoots Bruce and Bruce plays dead. As he plays dead, his right hand changes positions between camera angles.
Visible crew/equipment: In the museum rescue scene, as Batman lifts Vicki up to ride the Gauntlet/zipline to safety, an extra supporting hand can be seen around her waist as they cruise out of the frame.
Audio problem: When Vicki is kissing the Joker's arm near the end, the sound of her kissing is a fraction of a second off, enough to be noticeable.
Continuity mistake: When Vicki and Bruce take their plates to finish the supper in the kitchen, Vicki grabs her glass twice.
Continuity mistake: When the Joker is watching the pictures that his henchman gives him, he puts the one with Alexander Knox on the table. Then, he looks at Vicki's picture and there's now another picture on the table.
Continuity mistake: Vicky Vale's first name is V-I-C-K-I in the credits. On the cover of the magazine, it's spelled V-I-C-K-Y.
Continuity mistake: When Batman collects the balloons' cables in his flying vehicle's anterior contraption, he gets 6 or 7 cables caught, but when he closes the scissor-like mechanism, there are only 5 visible cables. Also, when he collects them, they gather at the back of the mechanism, but when he closes it, they are neatly caught in small notches.
Continuity mistake: After electrocuting the guy at the end of the table in the crime-bosses scene, Joker (Jack Nicholson) clearly tries to put the scarf into his chest pocket but fails and lowers his hand while still holding it. But in the next shot the scarf is perfectly in place.
Continuity mistake: Whenever shots show the view looking down on the ground when Batman and Vicky are hanging from the cathedral, it only shows two spotlights shining upwards from the ground. In other shots just showing the upper part of the cathedral, there are three or four beams visible. Also, the movement of the beams from the ground and the ones actually on the actors don't correlate between shots.
Continuity mistake: When Batman is first seen at the beginning of the scene at Axis Chemicals, he pulls a thug over a rail and hangs him from it. But when we see Batman standing over the rail, the thug is hanging from a pulley on the ceiling.
Answer: He was suspicious, but when she first entered the penthouse and Grissom said to leave their business meeting, he noticed the sexy facial exchange Alicia and Jack gave each other.