The body of water which doubled as the "Mississippi River" throughout nearly all the river scenes was actually the lake used for the Johnny Weissmuller Tarzan movies made at M-G-M. This lake was also known as "The Lagoon" at MGM Studios because of its size. Several boats were moored there at the time of the big auction of studio properties, including the scaled replica of the "Bounty." The Lagoon was located on MGM's vast Backlot #3 at Overland and Jefferson Boulevards in Culver City, about one mile south of the studio's main lot.
Director George Sidney was forced to leave for a few days because of illness, so uncredited associate producer Roger Edens directed the beautifully shot, fog-enshrouded "departure" sequence, including the performance by William Warfield of "Ol' Man River." It is the one scene in the film that has been praised even by critics who detest this version of "Show Boat."
MGM vied for the rights to film "Show Boat" as early as 1938. Universal Studios had owned the rights to the musical since 1929, and had made earlier versions in 1929 (with different songs) and 1936. MGM had hopes of starring the reigning operatic duo of Nelson Eddy and Jeanette MacDonald in the roles of Gaylord and Magnolia. but when that didn't happen, they showcased new stars Tony Martin and Kathryn Grayson - in a kind of screen test as Ravenal and Magnolia in the Kern film biography Till the Clouds Roll By (1946) (and Grayson did eventually appear in the 1951 "Show Boat"). The third lead in the film, the biracial Julie, was considered at various times for Judy Garland, Dinah Shore, and Lena Horne. Shore, although not a major film star, did have a somewhat exotic visage at the time - her hair and eyes were very dark, and she did almost as many blues and torch songs as a band singer in the 1940's as did Garland. Horne mentions in her biography that she wanted to do the role of Julie badly, but only got as far as performing a single number in the "Clouds" film in the opening "Show Boat" vignette. America, after all, was still a segregated nation in 1950. Interracial romance was still taboo on screen - and Julie kisses and romantically interacts with her white husband several times.
The showboat built for the film (known as the Cotton Blossom) became an amusement park attraction in 1973, after MGM sold many of its props at an auction. Unfortunately, in 1995, it was dismantled and torn apart. For this film, the Cotton Blossom was built on top of a flat-bedded barge so that it could be towed into position by underwater cables for the musical number which opens the film. Even though the Cotton Blossom was built to exact specifications and was fitted with a stern paddle-wheel, the thrust of the paddle wheel would have been too strong to maneuver the boat in the studio lake. Too little thrust would have moved the boat very slowly if it moved the boat at all. Hence, it was necessary to move the boat into position by underwater cables. This underwater towing technique also made it easier for the boat to move into its mooring position at exactly the right moment when the musical number came to an end.
Ava Gardner's original vocal track of "Can't Help Lovin' Dat Man" and Annette Warren's dubbed-in vocal track of the song were both modelled on Lena Horne's rendition of it in the then-recent M-G-M biography of Jerome Kern, "Till the Clouds Roll By". Warren's vocal tracks of "Can't Help Lovin' Dat Man" and "Bill", not Ava Gardner's, were the ones that eventually ended up being used in the film.
When viewing the rough cut, Arthur Freed, George Sidney, and Roger Edens came away feeling that the picture was too slow. In the rough cut, the scenes of Ravenal and Magnolia becoming rich, before suddenly going broke, lasted much longer. Roger Edens cut the "rich" scenes to a mere three minutes which showed a montage of quick scenes without dialogue, set to an orchestral accompaniment of "You Are Love". In the final print of the film, this is immediately followed by the scene in which Magnolia and Ravenal, still wealthy, sing "Why Do I Love You?", and this does contain dialogue. The scenes that followed, showing the couple in poverty, were also drastically tightened before the film's release, though they also contained dialogue.
The Breen Censorship Office tried to raise an objection against the use of the "miscegenation sequence" in this film version of the show, but they were unable to do so because the 1936 film version had already used it and thus set a precedent.
The original choice for the role of Julie was Judy Garland, but she had since ended her contract with MGM, the idea of casting Garland was dropped. Both Lena Horne and Dinah Shore were next in line until the role finally went to Ava Gardner.
When preparations for this film version of "Show Boat" were begun as far back as 1944, Walter Huston and Ethel Barrymore were set to play Cap'n Andy and Parthy. Both finally had to back out of the production, and Huston eventually died before the film started shooting.
Poster advertisements for this film completely omitted Leif Erickson's name, while in the actual film credits, Erickson is billed before William Warfield (even though his role is smaller than Warfield's).
This was the first film shown on a television network in 1972. It made its network television debut on "NBC Monday Night at the Movies", on the night of January 3 of that year. (No films were shown on January 1 or January 2nd because of the football.)
The trivia item below may give away important plot points.
In the rough cut of the film, there was a sequence near the end, retained from the original Broadway show, in which a little old lady appeared reminiscing about Magnolia and Ravenal's romance. The two were supposed to listen to her monologue and then embrace. The old lady was subsequently edited out of the film entirely, because it was felt that her monologue slowed down the picture.