It’s no simple job to manufacture authentic, spontaneous celebrity photos. Enter the Twitter Mirror, just offstage at awards shows and in talk-show greenrooms. The Mirror is Twitter Inc.’s name for a tablet programmed for VIP events and adorned with a filigree frame. Celebrities stand before it, tap the screen, take a few moments to pose, approve the photo or retake it and send it out through the event’s Twitter feed. “Our job is to get everyone at home on Twitter to say, ‘Oh my God, watching TV with Twitter is so much fun,’ ” says Fred Graver, the company’s head of TV. Twitter executives have been meeting with television producers since last winter about using the Mirror as a real-time promotional tool for their broadcasts. “People sometimes say, ‘These Oscars can be a slog.’ We’re trying to give them an amazing view of what is coming up next and what people are doing off-camera,” Mr. Graver says.