What is the plane used in the flight to Nepal in the movie "Raiders of the Lost Ark" (1981)

It was called the BV 38 "Flying Wing", and was an experimental concept e in NAZI era Germany.

The Pan Am Clipper was a type of transoceanic airplane flown by Pan American Airways.

In 1936, Indiana Jones took the China Clipper from San Francisco to the Philippines, where he changed to another Pan Am flight to Kathmandu, on his way to find Abner Ravenwood in Nepal. Jones, sitting on a starboard side window seat, didn't notice that a man in a hat on a portside seat was monitoring him, instead of reading a magazine. Not interested in a beverage, Jones decided to nap as the plane took off.

http://indianajones.wikia.com/wiki/Pan_Am_Clipper

The Pan Am clippers were Boeing 314 flying boats

http://www.boeing.com/boeing/history/boeing/m314.page
http://www.clipperflyingboats.com/pan-am/boeing-b314