Roger Bushell was called “Bartlett” in the movie and played by Richard Attenborough. Steve McQueen’s character ‘Hilts’ was purely fictional. There were no Americans in the camp or the escape. The motorcycle scene was added at McQueen’s insistence because he was into motorcycles at the time.
Iirc, the Americans were separated from the UK forces soon after their arrival at the camp.
McQueen also did not make that jump.
Jim Garner did play a Canadian-American flier.
The movie said most of the men were composites. My understanding was much of the inspiration behind Hilts was Jerry Sage. Check out on Amazon for his autobiography. It was a very good read. Another good autobiography from one flier there was Lonesome Read by George Harsh. At one point he was in prison for life in a chain gang before the war. Another good book.
The Americans had three members on the escape committee and they helped digging the tunnel. But the Americans were separated before the actual escape. Robert Stanford Tuck also was moved right before the break or else he would have been in the escape.