Another subtle clue is where Hanlon turns the radio braodcast off when Columbo indicates Wagner might have been murdered. This came into play later on when questioning the call girl. He indicated that Wagner was murdered and her voice immeidiately changed into an eastern European accent.
It seems to appear that she knew about the circumstances about Wagner's death.
I might be in the minority but this is my favorite episode. Ahead of its time in the concept of a sports empire. Hard to imagine in 1972.