Mary Anne and I were discussing coincidence in story plots, and this quote came to mind but I couldn't quite remember how it went, and it proved remarkably elusive to track down. Eventually I found a variant of it in an old file on my hard drive, which led me roundaboutly to the book where it appeared: Haphazard Reality: Half a Century of Science, by H. B. G. Casimir, p. 97. Figured I ought to quote it here so I can find it more easily next time.
While Gamow and Landau were at the Institute, the three of us often went to the movies together, and we had a preference for lowbrow and lurid films. Sometimes we could persuade Bohr to come with us to see a Western or a gangster film we had selected. His comments were always remarkable because he used to introduce some of his ideas on observations and measurements into his criticism.
Once, after a thoroughly stupid Tom Mix film, his verdict went as follows: “I did not like that picture; it was too improbable. That the scoundrel runs off with the beautiful girl is logical; it always happens. That the bridge collapses under their carriage is unlikely but I am willing to accept it. That the the heroine remains suspended in mid-air over a precipice is even more unlikely, but again I accept it. I am even willing to accept that at that very moment Tom Mix is coming by on his horse. But that at that very moment there should also be a fellow with a motion-picture camera to film the whole business—that is more than I am willing to believe.”