Continuity mistake: When the Joker's henchmen are trashing the museum, one guy puts red handprints all over a portrait, later the Joker walks by the same portrait and the handprints are gone. (00:59:55)
Continuity mistake: As Vicki waits at the museum cafeteria, you can see "Fluegelheim Museum" is printed on the menu on her table. But when she escapes with Batman, the sign at the front entrance of the building says "Flugelheim Museum". (01:00:30 - 01:07:20)
Continuity mistake: During the Batmobile car chase scene, Batman bangs a left from the side street near Monarch Theatre, leading Joker's henchmen and several patrol cars on a straight path for a few seconds. But right before the car pileup in front of Monarch Theatre, Batman is seen turning left onto the very same side street he came from to begin with. (01:08:00)
Continuity mistake: At one point during the car chase through downtown Gotham City, the Batmobile maneuvers a sharp turn with the aid of a cable that launches from the driver's side and hooks onto a steel beam structure nearby. But as the Batmobile starts cornering, notice how the cable appears fastened in a different manner. Between shots, it has tied itself completely around the beam instead. (01:08:15)
Continuity mistake: After rescuing Vicki from the museum, Batman leads Joker's henchmen on a downtown chase with the Batmobile. One car on his tail causes a major pileup at the intersection near Monarch Theatre. A short time later when the unmanned Batmobile is making its way down the street, it passes right through that very same intersection. This time, however, there are no indications that a pileup ever took place just moments before. All mangled vehicles and debris have disappeared. (01:08:20 - 01:12:00)
Continuity mistake: Right before the Batmobile is forced to park in front of a tractor's plow, it drives down the same stretch of road twice in consecutive shots (note the swerving car). (01:08:35)
Continuity mistake: After Batman rescues Vicky he has a voice remote for the Batmobile. As the car approaches he orders the car to stop by speaking into the remote and then lowers it to his side. When the camera shot changes showing the car stopping right in front of him, he is still holding the remote to his mouth. (01:09:20)
Continuity mistake: In the scene where the Batmobile automatically drives to Batman's and Vicky's location, a couple of patrol cars start following the Batmobile. When the Batmobile reaches Batman, they have mysteriously disappeared. (01:12:16)
Continuity mistake: When Joker is at the top of the building and taunting them, his chin is red (presumably from his blood when Batman socked him in the jaw.) After he falls off the building, and we see him lying on the ground, his chin is not covered in blood like it was before. (01:50:45 - 01:54:35)
Continuity mistake: When Batman initially fires the rope around Joker's ankle at the end, the rope only goes around the statue's legs. The next time we see it, it's somehow re-tied itself, and is now looped around the statue's backside. (01:52:55)
Continuity mistake: After asking Joker if he's ever danced with the devil in the pale moonlight, Batman throws a right hand punch. However in the following shot Joker is seen getting hit with the left fist instead. (01:54:30)
Continuity mistake: During the beginning of the parade sequence, the green-haired, big-nosed balloon is shown being decently high with the Joker's float underneath it. Yet when the Joker is shown dancing in a few close up shots, the face of the balloon is directly behind him.
Continuity mistake: When the "automated" Batmobile is sent into Axis Chemicals to blow it up, six of the Joker's men are shooting at it before it explodes, killing or seriously injuring everyone. Three of these same henchmen are also on the Joker's parade float at the very same time or very shortly afterwards in Gotham Plaza and one of them flies the Joker's escape copter at the end of the movie.
Continuity mistake: When the Joker is shooting Carl Grissom wildly, you can hear the sound of the glass behind him being hit only once. Later when the Joker is sitting at his desk, you can see two bullet holes to the left in the glass.
Continuity mistake: During the Joker's parade, shots looking at the Joker from the side show that his float passes the same shop twice.
Continuity mistake: When Joker's dead body is shown, the rope around his leg that was tied to the gargoyle is gone.
Continuity mistake: In the scene where Joker has broken in on the mayor's televised speech to the citizens of Gotham to challenge Batman to a "big duke-a-roo", Bruce freezes the live broadcast on a close-up of the Joker. He then flashes back to his parents murder. After the flashback, he looks again at the freeze frame picture of the Joker, but it is a different picture. When he freezes it, Joker's eyes are closed. When he comes back to the picture, his eyes are open.
Continuity mistake: When Batman jumps off of the remaining bell at the top of the cathedral, the goon uses Batman's momentum to throw him into a set of stairs, his trajectory parallel with the near wall. Since the goon wasn't standing near the wall when he threw Batman, this angle would not be possible to achieve.
Continuity mistake: When Joker and his goons are trashing the paintings, Joker writes "Joker Was Here" on the painting by the statue. In the next shot the painting disappears.
Continuity mistake: When Bruce smashes the vase in Vicki's apartment, it's further from the wall in the initial shot than when we see it actually smash in the close up.
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.