The production then moved to Stockton , California to depict a scene involving Al aboard a train . The Vietnam War sequences were filmed in Modesto , California , where the art department found difficulty in pinpointing filming locations , as the entire area was flooded . The use of helicopters during filming was the subject of frequent discussions with the Federal Aviation Administration ( FAA ) , following an accident during the production of '' Twilight Zone : The Movie '' ( 1983 ) . The special effects department used fifteen 20-gallon drums of gasoline rigged with explosive charges to depict a napalm strike . A total of four cameras were used to film the explosions . Principal photography concluded in early August 1984
accident
Twilight Zone accident
Birdy (film)