Correctable until the official puts the ball at the disposal of B1 (that would include the entire time out).
Afterwards, too late. Then the problem is: what do you do? The board operator probably stopped the clock when he started tooting the horn.
1. Count 1.5 seconds, blow whistle, game over.
2. Blow whistle, scold table, give ball back to B for 1.5 seconds, game over.
After either (1) or (2): run.