It was Fred Astaire's idea that he and Gene Kelly perform together in a new dance number in the film. Astaire was afraid that if he and Kelly just stood around and talked to each other, the audience would think they were too old to dance any more. As of the date of the film's release in May 1976, Astaire had just attained his 77th year a week earlier, and Kelly was to turn 64 that August.
One of only two films in which Fred Astaire and Gene Kelly danced together. The other was Ziegfeld Follies (1945).
Because the "Merry Widow Waltz" never comes to a musical conclusion in The Merry Widow (1934), the final thirty-two bars of the sequence as presented in That's Entertainment, Part II (1976) are actually borrowed from MGM's remake The Merry Widow (1952), while the visuals accompanying them remain from the 1934 version.
During the clip from Kiss Me Kate (1953), Gene Kelly identifies 'Ann Miller & Company,' without giving the names of the other dancers. A few moments later, Fred Astaire identifies Bob Fosse and Carol Haney. Bobby Van, Tommy Rall, and Jeanne Coyne remain unidentified.