The film is set in the world of bullfighting in the first half of the 20th century (1920s), and it is true that a bullfight is depicted in the film. Whether any animals were actually harmed in the making of the film - eg whether an actual bullfight was shown, or whether the effects were achieved in some other way - has not yet been confirmed. However, a number of animal cruelty protestors have already started organising petitions against it.

The issue has had a lot of attention because the film has been so successful.
It has already won a prize at the San Sebastian film festival, and is expected
to be the Spanish entry for the foreign language category at the next Academy
Awards. This is why some people are asking for the film to be boycotted at the
awards or for the nomination to be withdrawn. However, others say it is not yet
known whether animals were actually harmed, while others again point out that
bullfighting is part of Spanish culture.