"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."

When considering ways to change the course of the island, Dr. Dolittle says elephants cannot swim. Elephants are excellent swimmers, which he should know.

In the general release version of the film, the songs "Where Are The Words", sung by Anthony Newley, and "Something in Your Smile", sung by Rex Harrison, were omitted.

Featured in Film Review: Richard Attenborough (1968)