Only one official missed the handoff - the official administering the inbound pass. The other two have other areas of responsibility to watch. If all three are watching the inbound pass, no one is paying attention to what is happening on the baseline, in the paint or at the 3pt line.
That being said, the inbounding official clearly missed it, and I guarantee he'll regret it when viewing the film. He and I worked high school games together back in the day. I had, and still have, great respect for his body of work. He's a class act, a stand-up guy, and will be haunted by it.