Complex sentence: The film was produced using a combination of archival materials, including letters, photograph, paintings, and diaries from members of the Donner Party, as well as new footage shot of the trail the Party journeyed along in Oregon and California.
Split into simpler sentences: The film was produced using a combination of archival materials, including letters, photograph, paintings and diaries from members of the Donner Party. New footage was shot of the trail the Party journeyed along in Oregon and California.