Illegal number ???
 

Penalized when discovered: The head coach shall not permit a team member to participate while wearing an illegal number; Penalized when discovered. A maximum of one technical foul shall be charged directly to the head coach regardless of the number of offenders. The team member with the illegal uniform number may participate without further penalty and is not required to change his/her number. If no changes are made to the scorebook, no infraction has occurred.

What if said player participates, unbeknown to an official, and is then substituted for, and is sitting on the bench? Is it too late to penalize?

The penalty says when discovered, not while being violated.

I would charge the HC with a technical foul.

But once a player has participated in the game and the clock has run is not that player considered legal?

So once he is legal why wouldn't he remain legal?

How about this - I notice that one of their players has an illegal number, but the refs don't notice it. I keep it in my hip pocket (just in case). Sure enough, it's the other team's ball, 30 seconds left and we're down 1.

"Hey ref, isn't that an illegal number that player is wearing?"

Do I get two shots and the ball?

If it's a Player, yes.

If it's bench personnel, less clear (especially if they haven't been in the game).

Has anyone ever seen an illegal number in a regular season, varsity or college game? (at other levels, this rule is generally "ignored", at least around here)

Last year I had a player wearing #9 an in another game a girl wearing #27.
Both of these games occured well into the season and I am the 1st one to recognize that the numbers are illegal. What were the other officials doing???

Once the ball becomes live, a team member who should not be in the game because of substitution restrictions or another such rule becomes a legal player, but his uniform doesn't also magically become legal.