Thank you so much Dave! Indeed one of the challenges was finding a way to properly showcase the lives of the Oceanic Flight passengers before the crash.
The majority of the title design sequence is 3D. However, the horse in Kate's shot is stock footage I purchased from Filmsupply. Initially, it was 3D, however, I got great feedback from both (Aaron and Theo - mentioned in special thanks) suggesting that live footage was probably a better solution. And the fire in all of the shots used is stock, excluding the plane intro. The shots where I used backplates, were the following: intro - clouds, Charlie - wide shot, Hurley - wide shot, Jin and Sun - wide shot, and the final shot of the island.
Michael Giacchino's music during the series definitely gave chills. Very emotional indeed! Even though the project is complete. At some point, I might try to find a sound designer to see how this could be potentially more epic.
Hope this helps in any way. Once I get some time, it should be more apparent how elements were built in a BTS montage.