Audio problem: When Thornhill and Kendall reunite after the shooting, they are obviously on a soundstage and not on location in the wilderness. There is absolutely no background noise, which is impossible in the outdoors: leaves rustling, birds calling, water trickling, wind gusting, etc. prevent the complete silence depicted by the movie. The quality of the actors' voices also sounds like indoors rather than an open space. (01:46:30)
Audio problem: When Thornhill and Kendal are having dinner on the train, at one point Kendal says "I never discuss love on an empty stomach". Watch her lips and you'll see that Evas Marie-Saint is actually saying "I never make love on an empty stomach". The scene was clearly redubbed.