 This movie was shot in Munich, Germany, but the producers had to go  outside of Germany to recruit enough little people to play the Oompa  Loompas (one of the many tragic legacies of the Nazi era). Many of  the people cast as Oompaloompas (German or otherwise) did not speak  English fluently, if at all. This is why some appear to not know the  words to songs during the musical numbers.