While filming in the jungles in the Philippines, Michael Caine seemed to have an unerring sense of direction and always managed to find his way about. However, filming in the jungles created on the studio back lot in Hollywood was delayed on the first day, as Caine had managed to get himself lost.
Director Robert Aldrich refused Cliff Robertson's request to attend the 1969 Academy Awards ceremony, as a flight from the Philippines to Los Angeles and back would be too time-consuming. Robertson won the Oscar - for Charly (1968) - and the crew presented him with a mock statuette made out of wood. According to Turner Classic Movies host Robert Osborne, after the Philippine location shooting was over, Academy of Motion Pictures Arts & Sciences President Gregory Peck greeted the cast as it disembarked at Los Angeles International Airport. Robertson was holding his fake Oscar when he got off the plane. As he was approached by Peck with the real statuette, Robertson threw the wood "Oscar" over his shoulder. The fake Oscar hit Michael Caine in the forehead, and caused him to bleed profusely.
The US Navy's base at Subic Bay in the Philippines was a perfect location, as it had all the necessary amenities as well as having rain forest on one side and salt water on the other, in addition to its proximity to the city of Manila.
Robert Aldrich told the studio that he would accept "anybody by Cliff Robertson" for the leading role. His refusal to allow Robertson to attend the Academy Awards ceremony in 1969 was seen as a way to extract revenge on the studio.