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.