Group nouns can be singular or plural. This is not a grammar point – it depends on whether your mind sees a singular homogeneous group or a number of discrete individuals: the football team that you support is the best in the country, but who are they playing next week? It is, however, best not to mix number when dealing with such nouns. This is from today’s Guardian (my emphasis):
Any prime minister, however powerful, serves as a member of a cabinet. When that cabinet loses faith in him or her, and its members start saying so in public, the leader cannot stay … The cabinet knows Mr Brown is leading them towards a terrible defeat. They are not seeking revenge for the past. They want Labour to have a chance for the future.