In this episode, guest star Sal Mineo plays a former classmate of Robbie. Mineo, who was born in 1939, was actually 5 years older than Don Grady, who was born in 1944.
The title describes one of the most prominent symbols of the struggle of the United States during the American Revolution. Rung on the day the Declaration of Independence was passed, it hung for years in Independence Hall in Philadelphia and even has inscribed on it "Proclaim LIBERTY throughout all the Land". The distinctive occurred/was discovered when it was rung upon the death of John Marshall, Chief Justice of the Supreme Court.