4 players then 1 enters
 

After a time out, ball is now live. Not a substitute, one of the players that was in the game before the time out and just didn't enter after the time out until the ball was live. The official sees him enter the court. Is there a penalty?

Yes. Technical foul.

Edit: Citation is 10-1-9

Bart,

I believe that there is new interp on this - depends on advantage gained??? If the confused player just enters the fray to catch up, then no penalty. If he enters just in time to lead a snowbird, then T is warranted. I know a lot of posters use to rule this way anyway but I believe the FED has come around to their way of thinking on this play.

Oops!
 

Re-read the interp - it is a T after a timeout for not returning at the same time. If the same thing happened after a multiple sub process then judge on advantage gained.

Sorry.

I think that interp is regarding mass substitutions, not following a TO?

It discusses both situations. The rulings are different.