<Li> Frank Welker provided the vocal effects for gorillas . </Li> <Li> Gary A. Hecker and Peter Elliott provide the gorilla vocalization . </Li> <P> After the success of The First Great Train Robbery, Crichton decided to write a screenplay specifically for Sean Connery, as the character of Charles Munro, an archetypal "great white hunter" akin to H. Rider Haggard's hero, Allan Quatermain . The film was envisioned as an homage to classic pulp adventure tales, and Crichton successfully pitched the movie to 20th Century Fox in 1979 without a fleshed out story . The film ran into problems however when Crichton learned that he could not use a real gorilla to portray the character of Amy, which was a breaking point for him and he left the project . From there, it was offered to several directors including Steven Spielberg and John Carpenter who both passed . A brief attempt was made to revive the project in the late 1980s but to no avail . Ultimately Frank Marshall would go on to direct the film in the 1990s with little, if any involvement from Crichton . </P> <P> Congo opened with a weekend total of $24,642,539, eventually going on to gross $152,022,101 worldwide ($81,022,101 domestic) theatrically versus a $50,000,000 budget . </P>

Did they use real gorillas in the movie congo