Banned Episode: For a period of time in the 1960s, networks stopped airing the final season episode "The Ricardos Visit Cuba", due to the then-strained relationship between the U.S. and Cuban governments.
Desi Arnaz demanded that the second act of the episode "Lucy Tells The Truth" be rewritten. The plot involves Ricky, Fred and Ethel betting Lucy that she could not tell the truth for 24 hours. The original second act involved an IRS agent coming to the apartment to audit Ricky, and Lucy being forced to tell him about Ricky cheating on his taxes. Desi balked at the idea of Ricky cheating on his taxes, and a new second act was written.
The Danza: Lucille Ball as Lucy Ricardo. She did the exact same thing in her two new shows, despite being different characters. Vivian Vance (who played Ethel) was so sick of being called "Ethel" on the street that when she appeared on either of the spin-offs her character was always named Viv, Vi, or Vivian.
Funny Character, Boring Actor: While Lucille Ball is known as one of the funniest women on television, she actually didn't think she was that good at improvisation, and would often rehearse a scene endlessly until she thought she had it just right.
George O'Hanlon as Charley Appleby. You might not recognize his name or appearance, but as soon as he speaks you'll recognize him as the voice of George Jetson.
Arthur Q. Bryan as Mr. Chambers. You also might not recognize his name or appearance, but as soon as he speaks you'll recognize him as the voice of Elmer Fudd.
"The Young Fans" guest starred Janet Waldo (Judy Jetson).
Missing Episode: The Christmas Special was not included in syndication packages in order to prevent the episode from airing out of season, and also because of a supposed lack of interest in Clip Shows.
The Pilot was not intended for public broadcast, but it might also qualify. After CBS approved the show, Lucy and Desi gave a kinescope of the pilot to their friend Pepito Perez, who guest-starred. Since no one saw it afterward except for Pepito, his wife, and their friends, archivists spent decades assuming it got lost altogether. Pepito's widow finally brought it out of hiding in 1990. It took over 20 more years for CBS to find the uncut 35mm negative for the pilot.
Almost the entire plot was reused for an episode with Pepito replaced by a considerably less creepy clown.
Real-Life Relative: As mentioned, Lucille Ball and Desi Arnaz really were married for more or less the entire length of the series.
Rerun: As mentioned, the show's creators invented this trope.
And made a damn fortune off it. The network didn't know how much money could be made off of the reruns, and so they gave all the rights to Lucy and Desi. Enough for them to run their own major studio empire and be the executives in charge of shows like Gunsmoke, Mission: Impossible, The Untouchables, and Star Trek: The Original Series. Lucille and Desi's family still makes royalties off the show, and considering it's never been out of syndication, well...
Lucy has been quoted to say "We figured we couldn't lose. We'd ether make money off the deal, or at least we'd have the best set of home movies in the world."
Throw It In: The 1952 episode "Cuban Pals" features Ricky attempting to translate Lucy's questions for his Cuban friends. Desi Arnaz mistakenly translates one question in English, resulting in him almost doubling over in laughter onscreen for almost a minute.
Another is the scene in Hollywood when Lucy's fake nose catches on fire and she dunks it in a glass of water to extinguish it. It's notable because Lucille Ball was a very strict perfectionist who rehearsed scenes tirelessly, and that was one of the few times where a Throw It In moment wasn't thrown out.
It probably didn't hurt that reportedly Lucy was very concerned about the safety of a lit wick so close to her face, and figured better not push her luck with a second take.
"Lucy Goes to Scotland" would have aired in full color, if not for CBS' inability to afford color film. The episode was later colorized in 2007, as a bonus feature for a complete series DVD set of I Love Lucy and Lucy Desi Comedy Hour.
After the Hollywood Arc was over Desi suggested a Spin-Off taking place in their Hollywood hotel with Bobby the Bellboy as the main character as he deals with guests (he'd be given a female costar to play his girlfriend and get him involved in hijinx ala Lucy), but nothing came of it. With this in mind, the episodes featuring Bobby could be considered a Poorly Disguised Pilot.
Toward the end of the run Desi Arnaz asked William Frawley and Vivian Vance if they would like their own Spin-Off show after I Love Lucy's cancellation. Frawley readily agreed, sensing a very financially lucrative opportunity. Vance declined, however, in large part because of the hatred she and Frawley had for each other both on and off the set.
Lucille Ball originally wanted the roles of Fred and Ethel to be played by longtime friends and comic foils Gale Gordon and Bea Benaderet. However, at the time, Gordon was already committed to play bellowing principal Osgood Conklin on Our Miss Brooks, a role which he originated on the radio, while Benaderet was committed to play next-door neighbor Blanche Morton on The Burns And Allen Show. Another longtime friend of Ball's, Barbara Pepper, who later went on to play Doris Ziffel on Green Acres, was also considered to play Ethel. Unfortunately, however, by that time, Pepper had been drinking very heavily after her husband, Craig Reynolds, passed away in a tragic motorcycle accident. With Frawley, whose fondness for the bottle was legendary, already cast as Fred, Desi Arnaz felt he couldn't take the chance of having the responsibility of keeping two people in line.