It’s clear what Norris Cole is thinking here. He’s the point guard, and the big man inbounds the ball to him.
But when he flipped the ball from behind the baseline to Hassan Whiteside, Cole technically inbounded it. So, by giving it back to Whiteside out of bounds, it was a turnover.
Obviously, Whiteside should have also known better (and the turnover was scored as his), but Cole was directing the action.
And unfortunately for Cole, this screw up mattered. The Heat lost, 102-101, when Cole’s last-second 3-pointer missed.