According to director Mark Rydell, Vince Edwards had a gambling problem. Edwards demanded to film all of his scenes first, so that he could leave the set and go to a racetrack. According to Harry Landers, Edwards also constantly asked the cast and crew for money with which to gamble and leave the set for hours at a time.
The five symbols written on the blackboard at the start of each episode represent man, woman, birth, death, and infinity.
Dr. Zorba was originally named "Dr. Rosenberg". But ABC insisted his name to be changed, because they did not want the character to be Jewish. Creator James E. Moser cast Sam Jaffe to play Zorba with a Yiddish accent to emphasize that the character was meant to be Jewish.
Ben Casey was based on real-life neurosurgeon Dr. Allan "Max" Warner. Dr. Warner later changed his specialty to psychiatry, because he believed that his association with the show prevented him from being a board certified neurologist.