Michael Kidd (choreographer) broke his leg during rehearsal while showing a routine to dancers.

Ann-Margret made a screen test for the role of Irene Molloy.

Louis Armstrong was only on set for a half-day and did his shots in one take.

Pat Finley and Sandy Duncan made a screen test for the role of Minnie.

Tommy Tune's movie debut.

Also considered for the role of Dolly was Elizabeth Taylor, who was passed on because she couldn't sing. Doris Day and Shirley MacLaine (who played Irene Molloy in the non-musical predecessor The Matchmaker (1958)) were both briefly considered as well. Carol Channing was never considered for the role because it was felt, despite her Oscar nomination for Best Supporting Actress in the musical Thoroughly Modern Millie, that she could not carry a film of this stature despite being one of Broadway's top leading ladies.

Also in the original musical, Cornelius Hackl and the Widow Molloy sing "It Only Takes a Moment" in the courtroom during Horace Vandergelder's trial; in the movie, however, they sing "It Only Takes a Moment" in Central Park. The entire arrest and trial sequence was dropped for the movie version.

Among those who originally tested for the role of Gussie Grainger/Ernestina Simple were Jo Anne Worley and Peg Murray. Among those who tested for Ambrose Kemper was Ron Rifkin.

During filming, Barbra Streisand and Walter Matthau fought bitterly. He disliked her so intensely that he refused to be around her except when required to do so by the script. He is famously quoted as telling Barbra that she "had no more talent than a butterfly's fart". Interestingly, he is clearly seen in the audience at Barbra's One Voice concert at her Malibu ranch, where invitation-only guests paid $5,000 per couple to help establish the Streisand Foundation, which supports numerous charitable organizations. Apparently, Walter Matthau did not hold grudges.

In the final shot Horace kisses Dolly in front of the church. Walter Matthau detested Barbra Streisand so much that he refused to kiss her. To get around this he leaned near her and the camera was positioned so that the angle makes it appear that he kisses her when, in reality, his face was several inches from hers

In the Harmonia Gardens, the back wall behind the hat check girl, is the wall from the ballroom of the Von Trapps Villa in The Sound of Music.

In the original musical, Vandergelder was supposed to crash a dance number called "Be My Butterfly," after which he was arrested and charged with disturbing the peace. Dolly visits him in his holding cell at the courthouse, and this is where she sings "So Long, Dearie." For the movie, that number was dropped, and Dolly sings "So Long, Dearie" at the train station.

In the parade scene, the YWCA marching unit was the award-winning California High School Drill Team, under the direction of Ms. Jackie McCauley. The group was selected by Twentieth Century Fox based on their performance in the Hollywood Santa Claus Lane Parade on the Wednesday evening before Thanksgiving Day, 1967. The marching band in white uniforms was the UCLA Marching Band. The band in red and black uniforms was the San Fernando Valley Youth Band.

Leading UK DVD retailer HMV noted during an analysis of its 3rd quarter figures (July-September) for 2008 that "Hello, Dolly!" had sold more copies in this period than in the all the quarters combined for the previous 10 years. This was put down to the popularity of WALL·E which features clips from "Hello, Dolly!" at several key points.

Many of the massive fake buildings constructed on the outdoor back-lot sets in California to stand-in for turn-of-the-century New York City concealed working oil wells.

None of the original Broadway cast appeared in the film version.

On a break from filming, Walter Matthau and Michael Crawford visited horse races nearby and saw a horse named Hello Dolly. Matthau refused to place a bet on it because it reminded him of Barbra Streisand, whom he detested. Crawford placed a bet on the horse. It won the race and Matthau would not speak to Crawford for the rest of the shoot unless absolutely necessary.

One of the horse-drawn buses used in the New York scene in the beginning of the movie (Dolly is briefly seen descending from one) is still in use. It is part of the Krewe of Orpheus parade in New Orleans and can be seen every Lundi Gras, still drawn by horses. A calliope has been installed on the upper deck.

The facade of the Harmonia Gardens still stands as of 2010 on the 20th Century Fox lot, though the park across the street is long gone.

The fifth-highest grossing film of 1969.