Bruce: knows he has to introduce Jason to the public, so he takes him to an event that might interest him at least a little — one about cars
Also, Bruce: gets so caught up in his role as Brucie that he stop checking in with Jason to see how he's doing
Jason, less than an hour into the event, after seeing all the car models, makes eye contact with Bruce and nods toward the door: Bruce gets the message, I'm going home.
Bruce, two hours later, forgetting that he is Batman, in total “new” parent panic: I lost my baby!
Crowd: We’ll help you look! He’s probably in the bathroom!
Bruce, after half an hour of searching, remembering that he is Batman: I should call Alfred to check the batcomputer…
*Bruce's cell phone: 20 missed calls from Alfred*
Bruce, dialing: Alfred, I lost Jason…
Alfred, interrupting: Master Jason returned home alone two and a half hours ago. You would know this if you had answered your phone. He walked across Gotham on foot, alone. In the evening.
Bruce: Oh...
*Two and a half hours earlier*
Jason ringing the doorbell of the mansion: Alfie, could you open the door for me, please?
Alfred: Of course, Master Jason. May I ask, my dear, what are you doing here so early?
Jason, proud of himself: I got bored with the event, so I came home. I nodded to Bruce and left.
Alfred: Did someone drive you here?
Jason: No, why would they drive me here? I took a walk.
Alfred, preparing to call Bruce to ask why he thought it was a good idea for a child to walk alone through Gotham at this hour: I see…