Continuity mistake: At Gotham Globe when Vicki and Knox are talking about wildlife at the desk, Vicki's black shirt conceals her wristwatch between shots. (00:13:50)
Continuity mistake: When Knox walks into Gotham Globe and gets mocked about his recent Batman article, a co-worker hands him a funny Batman drawing just to rub it in. But watch as a coffee cup on the worker's desk turns itself completely around between shots. (00:13:10)
Factual error: It would take even a very strong acid a lot longer than a few seconds to eat through the thick metal bolts holding up the bell. (01:44:00)
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.
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.
Other mistake: In the scene at the beginning, when the robbers take Harold's wallet, the robber who had the gun says "American express card" but, when he says "don't leave home without it" the subtitles say the goon on the left says it, even though you can see the goon on the right move his mouth. (01:04:30)
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.
Continuity mistake: In the scene where Joker smashes a mirror on the surgical instrument table, a large fragment breaks off and hits the floor. That fragment somehow appears on the tabletop seconds later. (00:35:10)
Continuity mistake: When Knox takes the funny Batman sketch from his co-worker, his right hand jumps to a different part of the paper between frames. (00:13:10)
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: In the scene where Joker is admiring a black and white photo of Vicki, watch as the crayons in his pink bucket on the table keep changing between shots. (00:53:05)
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.