The "valentine" opening credits seen in syndication were *not* the original opening credits. When the series originally aired on CBS, the credits featured animated stick figures of Lucille Ball and Desi Arnaz along with the sponsor's product - Phillip Morris cigarettes, for instance. The "valentine" credits were added when CBS began rerunning the series in 1958.
References to the series' original sponsor, Phillip Morris, can be seen in some episodes. Most notable is the scene in I Love Lucy: Lucy Does a TV Commercial in which Lucy dresses up as Johnny the Bellhop, the Phillip Morris icon.
Gale Gordon was the first choice to play Fred Mertz, but he was unavailable. When they came across William Frawley, Desi Arnaz wanted him, but he was told that Frawley would be a poor choice because he was a womanizer, a gambler, and a drunk. Arnaz said, "He's perfect!"
This was one of the first TV shows to be filmed in Hollywood, at a time when many shows were done live in New York. It pioneered the use of three cameras simultaneously, and the results were high-quality prints of a classic comedy series preserved for future TV audiences.
Three "flashback" episodes were shown during the period when Lucille Ball was recovering after giving birth to Desi Arnaz Jr.. These episodes were filmed in advance after Ball found out she was pregnant.
Ethel was from Albuquerque, New Mexico and her father ran the candy store. Also, one of her neighbors was Betty Ramsey, who would later become a neighbor of Ethel's and Lucy's when they moved to Connecticut in the final season.
Lucille Ball decided to go ahead with the series after having a dream in which Carole Lombard - the screwball comedy actress who died in a plane crash and who was a close friend of Ball's - recommended she take a shot at the risky idea of entering television.
In 1990, a 16mm print of the original pilot episode was found. The opening titles and first few seconds of the opening narration were damaged beyond repair. This scene was reconstructed for DVD in 2002 with a re-recorded narration by Bob LeMond, 50 years after he originally recorded it.
In the episodes when the Ricardos and the Mertzes are in Hollywood, the backdrop of Hollywood outside of the Ricardo's hotel suite replicates the view as it would be have been seen from the top of the stages at the Desilu lot on Cahuenga Boulevard (now Ren-Mar Studios), two blocks to the west of Vine Street where most of the "I Love Lucy" episodes were shot. Most of the landmarks at Hollywood and Vine that are on the backdrop (except for the Brown Derby Restaurant, which was demolished in the 1980's) may still be seen at that location today, over fifty years later. The Capitol Records Building was under construction when these episodes were being filmed and is not seen on the backdrop. The "Beverly Palms Hotel" was a fictional hotel, but its interior and exterior set designs combined elements of the Hollywood Plaza Hotel, the Hollywood Roosevelt Hotel and the Bevery Hills Hotel.
During the course of living in their New York apartment the Ricardo's had three different telephone numbers. The first was MUrray-hill 5-9975, the second was CIrcle-7-2099, and the third was MUrray-hill 5-9099. In actuality these numbers were unused telephone numbers of the New York Bell Telephone Company. When the numbers were entered in to service the Bell company would advice the shows producers and give them a new number to use. Murray Hill and Circle were also actual call names used in Manhattan at the time.
Although they slept in twin beds throughout the entire run of the series, during the first two seasons of the show, 1951-1953, Ricky and Lucy slept in twin beds that were pushed together in the same box spring. Once little Ricky was born CBS suggested that the beds be pushed apart to diminish the impact of the suggested sexual history of Lucy and Ricky. The only time we see the Ricardo's in two bed pushed together again is when they first move to the bigger apartment in the Mertz building, however, subsequently after that the beds are pushed apart again.
The show started out as a radio program in 1948 called, "My Favorite Husband". And during the program, it was Dick Denning who played Lucy's husband. When CBS decided to take the show to television, it was Lucille Ball's idea to bring her real life husband, Desi Arnaz.
The writers mirrored the actors' real lives in presenting the character back stories. Lucy Ricardo, like Lucille Ball was born in Jamestown, New York, attended Celeron High School, and came to Manhattan as young woman. Ricky Ricardo, like Desi Arnaz, was from Cuba, and both led their own Latin America bands. Ricky and Lucy, like Desi and Lucy, eloped to Connecticut to get married. Ethel Mertz, like Vivian Vance, was from Albuquerque, New Mexico where they got their start in show business by appearing in the Albuquerque Little Theater. Like William Frawley, Fred Mertz was a Mid-Westerner who was raised on a farm and enjoyed a successful run as a vaudevillian.
There is a subtle hint in the series of the quick costume changes that go along with filming live TV shows: In many of the scenes where Lucy and Ricky are in bed, pay attention to when they are getting in and out of bed. Whenever they swing their feet in and out, you'll see that Desi Arnaz is wearing black dress socks with his pajamas and Lucille Ball is wearing stockings (you can see the reinforced toes and heels) under her pajamas/gowns.