Karl Malden was a member of the Group Theater in the 1940's, a company established by Lee Strasberg. Here he works with his daughter, Susan.
At the point in the series the show had gotten so popular that it was attracting large crowds when filming on location around the city. Large crowds of people can be seen in the background even at a vacant lot in an industrial area.
First TV appearance of Joe Spano, better known for "Henry Goldblume" in Hill Street Blues (1981) and "T.C. Fornell" in NCIS (2003), among many other movie and TV roles.