At the start of Season 5, the opening sequence featured Lucille Ball's head on an animated jack-in-the-box. Ball hated this sequence and it was changed back to the Season 4 version, which showed clips of Lucy in a kaleidoscopic fashion. This sequence remained until the end of the show's run. The "jack-in-the-box" sequence has never been shown in syndication since the 1970s.
The show ended in 1968 as a result of the sale of Lucille Ball's production company Desilu to Gulf + Western Industries in December 1967. Gulf + Western used their ownership of Desilu to create a television division for its other property, Paramount Pictures. Because Ball no longer owned Desilu, she no longer owned the show. She started a new production company and started a new sitcom, Here's Lucy (1968).
Frustrated with Joan Crawford's lack of memorizing her lines, Lucille Ball was said to have asked fellow producers if Gloria Swanson was available to film the episode instead (Ms. Swanson was not available).
For reasons which are not entirely clear, 30 episodes have entered the public domain - 2 are from the first season (black & white); 21 are from the fifth season (all episodes in that season, minus #18 "Lucy Puts Main Street on the Map" which is apparently still under copyright); and 7 are from the sixth season (seven of the first eight episodes, with #5 "Lucy Gets Her Diploma" apparently still under copyright). In series order, the full list of 30 public domain episodes are: "Lucy and Viv Put in a Shower", "Lucy's Barbershop Quartet", "Lucy and George Burns", "Lucy and the Submarine", "Lucy, the Bean Queen", "Lucy and Paul Winchell", "Lucy and the Ring-a-Ding-Ding", "Lucy Goes to London", "Lucy Gets a Roommate", "Lucy and Carol in Palm Springs", "Lucy Gets Caught Up in the Draft", "Lucy and John Wayne", "Lucy and Pat Collins", "Lucy and the Monkey" (aka "Mooney the Monkey"), "Lucy and the Efficiency Expert" (aka "Lucy and Phil Silvers"), "Lucy's Substitute Secretary", "Viv Visits Lucy", "Lucy, the Baby Sitter", "Main Street U.S.A.", "Lucy Meets the Law", "Lucy, the Fight Manager", "Lucy and Tennessee Ernie Ford", "Lucy Meets Sheldon Leonard", "Lucy Meets the Berles", "Lucy Gets Trapped", "Lucy and the French Movie Star", "Lucy, the Starmaker", "Lucy and Jack Benny's Account", "Little Old Lucy" (aka "Little Old Lady"), and "Lucy and Robert Goulet".
The series was originally intended to air for only one season. Ball and Desi Arnaz's studio, Desilu, was losing money. Arnaz persuaded Ball to return to series television only to help their studio become viable again. Ball agreed to do the show only if it aired on Monday nights like "I Love Lucy" (1951)_ had and if her former co-star, Vivian Vance, and her former writers would be involved.
Halfway through its final season, "The Lucy Show" changed production companies from Desilu to Paramount Television. As a result, the Desilu "merging circles/animated signature" logo was permanently retired and replaced by the Paramount Television "rising circle/changing text" logo for the show's final 13 episodes. (During the first half of the season, a Paramount copyright notice accompanied by a miniature Paramount logo and "Paramount Pictures Corporation" in its distinctive cursive font was shown beneath the Desilu logo.)