According to Robert De Niro, he and Billy Crystal briefly toyed with the idea of co-directing the movie before deciding to offer it to Harold Ramis, who accepted.
It was very important to Robert De Niro that the movie felt authentic. He and director Harold Ramis would drive around Little Italy in New York City looking for real people to cast.
Originally, the scene in which the couple is discussing their problems in bed with Dr. Sobel (Billy Crystal) was supposed to include only the woman and Dr. Sobel, but Crystal thought it would be funnier if the two of them were present. The man playing the husband is the head of the sound department for this movie, Les Lazarowitz, who, being a heavyset guy, made the scene even more comical. He deferred the sound mixing duties to his assistant, while this scene was being filmed. Coincidentally, Lazarowitz was the boom operator (uncredited) in the fruit stand scene of The Godfather (1972), which is parodied in this movie.
Robert De Niro suggested Chazz Palminteri for the role of Primo Sidone, having worked with him on A Bronx Tale (1993).