The musical instructor tells the children that his instrument is a "tuba". Although that is technically true, it is really a Sousaphone -- an instrument created by J. W. Pepper at the request of "March King" John Philip Sousa. The instrument that Columbo plays, on the other hand, is a traditional tuba.
90 minutes long
The "Music Center" in this episode is The Los Angeles Music Center, a complex which houses, among other halls, the Dorothy Chandler Pavilion, home for a number of years to the Academy Awards broadcasts.