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Jerome Robbins initially refused to work on the film unless he could direct it. Producer Walter Mirisch was nervous about handing the reins entirely over to Robbins, who had never made a film before, so he enlisted Robert Wise to direct the drama while Robbins would handle the singing and dancing sequences. Robbins developed a habit of shooting numerous takes of each scene, to the point where the film went over budget and behind schedule. This led to his firing.
The actors in the rival gangs were instructed to play pranks on each other off the set to keep tensions high.
The lyrics to "America" were substantially changed for the movie. There had been complaints that the Broadway version was too belittling to Puerto Ricans, in that the song mainly ridiculed Puerto Rico and Puerto Ricans. The movie lyrics emphasize the racism and discrimination that Puerto Ricans were subjected to in America.
Throughout the movie, Natalie Wood wears a bracelet on her left wrist, not for any aesthetic reason, but because she had injured her wrist in the scene of The Green Promise (1949) when she fell on the bridge that collapsed during the severe rainstorm, causing an unsightly bone protrusion on her wrist. She wore the bracelet to hide the injury. It became her trademark in all of her movies.
Riff and Tony repeat an oath of loyalty to each other: Riff says "womb to tomb" and Tony answers "birth to earth." On stage Tony's original answer was "sperm to worm," but this was changed for the movie because it was beyond the censorship standards of the time.
Russ Tamblyn (Riff) said that initially he was very unhappy with his dancing in the film, until Fred Astaire came over to him at the premiere and told him that he admired his dancing in it very much.