[BillyMac]

Originally Posted by Afrosheen

I’m wondering if say the play is an alley-oop with three seconds left and the throw-in is from the sideline. Clock starts without anyone touching it and the only thing that happens is that the ball bounces off the backboard untouched and then bounces out of bounds on the end line. Where would the play be resumed from?

This is a throwin violation, so it goes back to the original throwin spot.

7-6-2: … The throw-in pass shall touch another player (inbounds or out of bounds) on the court before going out of bounds untouched.
PENALTY: (Section 2) Following a violation, the ball is awarded to the opponents for a throw-in at the original throw-in spot.

With definite knowledge, which you seem to have, reset the game clock to three seconds.

5-10: ART. 1 The referee may correct an obvious mistake by the timer to start or stop the clock properly only when he/she has definite information relative to the time involved. The exact time observed by the official may be placed on the clock.
ART. 2 If the referee determines that the clock malfunctioned or was not started/stopped properly, or if the clock did not run, an official’s count or other official information may be used to make a correction.