With it all happening so quickly, at what point have you lost the opportunity to blow this play dead for the illegal throw in? By the time the player catches the 3/4 court pass, at the moment Black scores for Red, after they scored, etc.?
I would see a delay of game warning to Black and an inbound to Red on this play, and play from the point of Black scoring the initial basket in their opponent's basket (since you are Canadian, I am assuming FIBA terminology in this case applies - see other thread
).