"The Reluctant Vegetarian" was one of the hardest scenes to film, mainly because of the number of animals that had to sit still for a lengthy period. The cast had hours of rehearsal and preparation before filming started. The first take went very well, until Sir Rex Harrison stopped singing. Director Richard Fleischer asked him why, and Harrison said he heard him yell "Cut!" Fleischer denied it, and they were starting to argue about it when both heard a voice yell "Cut!" The guilty party turned out to be Polynesia the Parrot. Harrison said "That's the first time I've ever been directed by a parrot. But she may be right. I probably can do it better."
This movie set was no picnic. One of the fawns ate a quart of paint during a scene break, and had to have her stomach pumped. Gub-Gub the Pig had to be replaced several times during filming, because piglets grow very fast. Squirrels ate through several key pieces of scenery, requiring thousands of dollars in repairs. When Sir Rex Harrison sang in the field of sheep, he had to be sprayed down repeatedly for flies. The sheep urinated on him, forcing multiple retakes. One of the goats broke loose during a scene and ate director Richard Fleischer's script. The first several weeks of filming in Castle Combe were disrupted by torrential downpours, after the producers ignored detailed climate reports about the area's weather patterns. A disgruntled resident tried to blow up the set with a homemade bomb.
This movie was part of Twentieth Century Fox's attempt to duplicate the success of The Sound of Music (1965) by producing three expensive, large-scale musicals over three years. This movie, Star! (1968), and Hello, Dolly! (1969) were all released amidst massive publicity. All lost huge amounts of money. Several top studio executives lost their jobs, and the studio was in such dire financial straits that it only produced one movie in 1970. The studio finally recouped its losses in 1973, when The Sound of Music (1965) was re-released to theaters.
Samantha Eggar said of Sir Rex Harrison, "Yes, he was unkind and vitriolic and very mean-spirited, but he was also very funny, until, of course, he turned on me, too."