Executive Meddling: The original concept toed the line between "God Is Evil" and "Humans are just another of God's Wonderful Toys", but CBS fired the creator when he refused to write more idealistic episodes.
In fact (depending on your knowledge of minor celebrities and character actors), almost every episode can be thought of as "The One With (Insert Name of Famous Person Here)".
Some of the actors in it went on to become famous later leading to Retroactive Recognition, such as Zachary Quinto and Hayden Pannttiere.
NSYNC made a cameo as basically busker versions of themselves singing on the street.
What Could Have Been: Bill Cosby was originally going to make a guest appearance as the "Angel of Fun", but this was cancelled when his son Ennis was murdered. He subsequently appeared in two episodes as the Angel of Reconciliation. (He is sent to reconcile a father with a son the father thought was dead. Cosby's theme was "Never mind old quarrels, you should be glad your son is alive"...)