The Disadvantages of Multicultural workforce

More organization leaders are trying to overcome the challenges of managing a multicultural workforce so that they can reap the benefits.
Enhanced Risk of Discrimination
A diverse workforce presents increased a lot of discrimination. It means that if you put people together with distinguish skin color, culture, married status, etc. employees could use them against others.
Internal Communication
Through multicultural communication is usually benefit, internal communication is typically more challenging when employees have language and cultural barriers.
Management Time and Cost
The investigation of employee complaints regarding negative attitudes and harassment can take up a considerable amount of management time and cost, whether or not they are upheld. 

Source: http://www.ehow.com/info_8713415_disadvantages-multicultural-team.html
             http://www.referenceforbusiness.com/encyclopedia/Mor-Off/Multicultural-Workforce.html