Oh, and to respond to the intial poster - Memphis Belle finished its tour on May 17, 1943. He is correct that at that time, 25 missions was the requirement. As missions became safer, the requirement was upped to 30, then 35 missions IIRC as the war went on. I think medium bomber tours in the USAAF in the ETO may have been 50. Interesting to note though that Memphis Belle was not first; Hell's Angels of 303 BG finished its tour on 14 May 1943, beating the Belle by 3 days. Also, the crew of the Memphis Belle was a composite, and not all crewmen selected as the "official" crew had actually flown in the Belle during the 25 missions - in particular, Jim Verinis had moved on from co-pilot status to flying his own ship, but many of the other crew positions had seen substitutes, etc. Robert Morgan talks about all of it in his excellent autobiography.
All trivia, but interesting.
Good luck to the initial poster with his movie project, and feel free to post with additional questions here or contact members of the board via email; that is of course why we are here.