Continuity mistake: After Flash fixes the timeline, he is back in Bruce's Batcave and gives Bruce a letter from his father. Bruce is working at a station and his utility belt is there as he is working on it. When the camera pulls back before Flash runs off, his utility belt vanishes. (01:17:00)
Revealing mistake: During the flashback when we see Bruce Wayne murdered, Thomas Wayne is beating up Joe Chill while in the background, Martha can be seen cradling Bruce's dead body. As she picks him up though, the animators forgot to remove the still frame so it appears as if there are two corpses.
Chosen answer: He probably turned her over to the police. There's no knowing how much time passed between when he caught her and when he jumped on the roof to chat with Batman.
Casual Person