Macau (then a Portuguese colony) was substituted for Shanghai, while cinematographer Douglas Slocombe caught fever from June 24 to July 7 and could not work. Ford returned on August 8. Despite the problems during filming, Spielberg was able to complete "Temple of Doom" on schedule and on budget, finishing principal photography on August 26. Various pickups took place afterwards. This included Snake River Canyon, in Idaho, Mammoth Mountain, Tuolumne and American River, Yosemite National Park, San Joaquin Valley, Hamilton Air Force Base and Arizona. Producer Frank Marshall directed a second unit in Florida in January 1984, using alligators to double as crocodiles. The mine chase was a combination of a roller coaster and scale models with dolls doubling for the actors. Minor stop motion was also used for the sequence. Visual effects supervisors Dennis Muren, Joe Johnston and a crew at Industrial Light & Magic provided the visual effects work, while Skywalker Sound, headed by Ben Burtt, commissioned the sound design. Burtt recorded roller coasters at Disneyland Park in Anaheim for the mine cart scene.